Array substrate for in-plane switching mode liquid crystal display device and method of fabricating the same

ABSTRACT

An array substrate for use in an in-plane switching liquid crystal display device includes a gate line on a substrate; a data line crossing the gate line to define a pixel region having an aperture area; a thin film transistor disposed at one corner of the pixel region and connected to the gate line and the data line, the thin film transistor including a semiconductor layer; a common line spaced apart from and substantially parallel to the gate line; a common electrode extending from the common line and including a plurality of common electrode patterns, wherein an outermost portion of the common electrode pattern is substantially rectangle shaped within the pixel region and has a substantially circular opening in the middle thereof; a capacitor electrode overlapping the rectangle shaped common electrode pattern, the capacitor electrode connected to the thin film transistor; a pixel connecting line substantially parallel to the data line in the pixel region and connected to the capacitor electrode; and a pixel electrode disposed within the substantially circular opening, extending from the pixel connecting line and including a plurality of pixel electrode patterns; wherein an innermost pixel electrode pattern has a substantially circular shape and other pixel electrode patterns are patterned to have circular bands, and wherein the aperture area is circular banded shaped.

This application is a divisional application of U.S. patent applicationSer. No. 10/825,486, filed Apr. 16, 2004, now U.S. Pat. No. 7,202,928,which claim priority to Koran Patent Application No.: 10-2004-0025955,filed Apr. 14, 2004, and 10-2003-0072124, filed Oct. 16, 2003 all ofwhich are incorporated by reference for all purposes as if fully setforth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to liquid crystal display devices. Moreparticularly, the present invention relates to liquid crystal displaydevices implementing in-plane switching (IPS) where an electric field tobe applied to liquid crystals is generated in a plane parallel to asubstrate.

2. Discussion of the Related Art

A liquid crystal display device uses the optical anisotropy andpolarization properties of liquid crystal molecules to produce an image.Liquid crystal molecules have a definite orientational alignment as aresult of their long, thin shapes. The alignment direction can becontrolled by an applied electric field. In other words, as an appliedelectric field changes, so does the alignment of the liquid crystalmolecules. Due to the optical anisotropy, the refraction of incidentlight depends on the alignment direction of the liquid crystalmolecules. Thus, by properly controlling an applied electric field, adesired light image can be produced.

Of the different types of known liquid crystal displays (LCDs), activematrix LCDs (AM-LCDs), which have thin film transistors (TFTs) and pixelelectrodes arranged in a matrix form, are the subject of significantresearch and development because of their high resolution andsuperiority in displaying moving images.

LCD devices have wide application in office automation (OA) equipmentand video units because they are light and thin and have low powerconsumption characteristics. The typical liquid crystal display panelhas an upper substrate, a lower substrate and a liquid crystal layerinterposed there between. The upper substrate, commonly referred to as acolor filter substrate, usually includes a common electrode and colorfilters. The lower substrate, commonly referred to as an arraysubstrate, includes switching elements, such as thin film transistorsand pixel electrodes.

LCD device operation is based on the principle that the alignmentdirection of the liquid crystal molecules is dependent upon an electricfield applied between the common electrode and the pixel electrode.Thus, the alignment direction of the liquid crystal molecules iscontrolled by the application of an electric field to the liquid crystallayer. When the alignment direction of the liquid crystal molecules isproperly adjusted, incident light is refracted along the alignmentdirection to display image data. The liquid crystal molecules functionas an optical modulation element having variable optical characteristicsthat depend upon polarity of the applied voltage.

In a conventional LCD device, the pixel and common electrodes arepositioned on the lower and upper substrates, respectively, and theelectric field induced between pixel and common electrodes isperpendicular to the lower and upper substrates. However, theseconventional LCD devices have a very narrow viewing angle. In order tosolve the problem of narrow viewing angle, in-plane switching liquidcrystal display (IPS-LCD) devices have been proposed. The IPS-LCDdevices typically include a lower substrate in which a pixel electrodeand a common electrode are disposed, an upper substrate having noelectrode, and a liquid crystal interposed between the upper and lowersubstrates. A detailed explanation of a typical IPS-LCD panel will beprovided with reference to FIG. 1.

FIG. 1 is a schematic cross-sectional view illustrating a related artIPS-LCD panel. As shown in FIG. 1, upper and lower substrates 10 and 20are spaced apart from each other, and a liquid crystal layer 30 isinterposed there between. The upper and lower substrates 10 and 20 areoften referred to as an array substrate and a color filter substrate,respectively. A common electrode 22 and a pixel electrode 24 on thelower substrate 20. The common and pixel electrodes 22 and 24 arealigned parallel to each other. On a surface of the upper substrate 10,a color filter layer (not shown) is commonly positioned in a positionbetween the pixel electrode 24 and the common electrode 22 of the lowersubstrate 20. A voltage applied across the common and pixel electrodes22 and 24 produces an electric field 26 through the liquid crystal 32.The liquid crystal 32 has a positive dielectric anisotropy, and thus italigns parallel to the electric field 26.

When no electric field is produced by the common and pixel electrodes 22and 24, i.e., off state, the longitudinal axes of the liquid crystal(LC) molecules 32 are parallel and form a definite angle with the commonand pixel electrodes 22 and 24. For example, the longitudinal axes ofthe LC molecules 32 are arranged parallel with both the common and pixelelectrodes 22 and 24.

On the contrary, when a voltage is applied to the common and pixelelectrodes 22 and 24, i.e., on state, an in-plane electric field 26 thatis parallel to the surface of the lower substrate 20 is produced becausethe common and pixel electrodes 22 and 24 are on the lower substrate 20.Accordingly, the LC molecules 32 are re-arranged to bring theirlongitudinal axes into coincidence with the electric field 26.

Therefore, the result is a wide viewing angle that ranges, for example,from about 80-85 degrees in up-and-down and left-and-right sides from aline vertical to the IPS-LCD panel.

FIG. 2 is a plan view illustrating one pixel of an array substrateaccording to a related art IPS-LCD device. As shown, gate lines 40 aretransversely arranged and data lines 42 are disposed substantiallyperpendicular to the gate lines 40. A common line 50 is alsotransversely arranged parallel with the gate line 40 and is spaced apartfrom the gate line 40. The gate line 40, the common line 50 and a pairof the data lines 42 define a pixel region P on the array substrate. Athin film transistor (TFT) is disposed at a corner of the pixel region Pnear a crossing of the gate and data lines 40 and 42.

In each pixel, three common electrodes 44 extend perpendicularly fromthe common line 50, and two of the common electrodes 44 are disposednext to the data lines 42, respectively. A pixel connecting line 48 isdisposed next to and parallel to the gate line 40, and is electricallyconnected to the TFT T. Pixel electrodes 46 extend perpendicularly fromthe pixel connecting line 48 toward the common line 50. Each of thepixel electrodes 46 is disposed between two of the common electrodes 44parallel with the data line 42. Each of areas “I” between the respectivecommon electrodes 44 and the respective pixel electrodes 46 is definedas a block where the liquid crystal molecules are re-arranged by theelectric fields. In FIG. 2, there are four blocks in one pixel.

As shown in FIG. 2, the IPS-LCD device according to the related artre-arranges and operates the liquid crystal molecules using the electricfield generated parallel with the array substrate. Thus, it can providea wide viewing angle rather than the LCD device that forms the electricfield perpendicular to the array substrate. Recently, however, somemodifications have been developed in the IPS-LCD device in order tofurther increase the viewing angle.

FIG. 3 is a plan view of an array substrate for use in an IPS-LCD devicehaving multiple domains according to the related art. Some of thedetailed explanations previously explained with reference to FIG. 2 willbe omitted in order to prevent duplicate explanations.

In FIG. 3, a pixel connecting line 58 is disposed over a common line 60.Common and pixel electrodes 54 and 56, respectively, are elongated fromthe common and pixel connecting lines 60 and 58, respectively, in anup-and-down direction. Both the common and pixel electrodes 54 and 56have a zigzag shape with plural bent portions. The common and pixelelectrodes 54 and 56 are parallel to each other and alternatelyarranged. The zigzag shape defines the multi domains in the pixelregions symmetrically to the bent portions of the common and pixelelectrodes 54 and 56. The zigzag shape and the multi domain structuresimprove the viewing angle over the straight shaped structure of FIG. 2.

Moreover in FIG. 3, the pixel connecting line 58 overlaps the commonline 60 so that an overlapped area becomes a storage capacitor CST. Inparticular, the pixel connecting line 58 acts as one electrode of thestorage capacitor CST, while the overlapped portion of the common line60 acts as the other electrode of the storage capacitor CST. One of thepixel electrodes 56 is connected to a drain electrode 62 so that all ofthe pixel electrodes 56 can electrically communicate with the TFT T.

However, the IPS-LCD device having the above-mentioned multi domains hasa color shift problem based upon the viewing angles because of long andthin shapes of the liquid crystal molecules.

FIG. 4 is a graph illustrating viewing angle properties of a IPS-LCDdevice having the zigzag structure of FIG. 3. The IPS-LCD device havingthe zigzag-shaped common and pixel electrodes can have improved viewingangles in directions of ±90 and ±180 degrees, i.e., in right-and-leftand up-and-down directions, as illustrated by reference lines “IVa” and“IVb” in FIG. 4. However, the viewing angles are degraded in directionsof ±45 and ±135 degrees, i.e., in diagonal directions, as illustrated byreferences “IVc” and “IVd” in FIG. 4. Furthermore, a color shift alsooccurs based upon the viewing angles or directions.

When the voltages applied to the electrodes generate electric fieldsbetween the common and pixel electrodes, the liquid crystal moleculesrotate about 45 degrees in accordance with the electric fields. Then,gray inversion occurs due to the rotation of the liquid crystalmolecules. When the IPS-LCD is operated in gray mode, the IPS-LCDproduces a yellowish color in 45(+45) degrees declination with respectto the liquid crystal polarization because of the optical anisotropyproperties of liquid crystal molecules. The IPS-LCD also produces abluish color in 135(−45) degrees declination with respect to the liquidcrystal polarization because of the optical anisotropy properties of theliquid crystal molecules.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an array substrate foran in-plane switching mode liquid crystal display LCD device and methodof manufacturing the same that substantially obviates one or more of theproblems due to limitations and disadvantages of the related art.

An advantage of the present invention is to provide an array substrateand a method of forming the array substrate for use in an IPS-LCDdevice, which increase a viewing angle and prevent a color shift.

Another advantage of the present invention is to provide an arraysubstrate and a method of forming the array substrate for use in anIPS-LCD device, which provide uniform director of liquid crystalmolecules in all directions.

Additional features and advantages of the invention will be set forth inthe description which follows and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages, and in accordance with thepurpose of the present invention, as embodied and broadly described, anarray substrate for an in-plane switching liquid crystal display devicecomprising a gate line on a substrate; a data line crossing the gateline to define a pixel region having an aperture area; a thin filmtransistor disposed at one corner of the pixel region and connected tothe gate line and the data line, the thin film transistor including asemiconductor layer; a common line spaced apart from the gate line withbeing parallel with the gate line; a common electrode extending from thecommon line and including a plurality of common electrode patterns,wherein an outermost portion of the common electrode pattern issubstantially rectangle shaped within the pixel region and has acircular opening in the middle thereof; a capacitor electrodeoverlapping the substantially rectangle shaped common electrode pattern,the capacitor electrode connected to the thin film transistor; a pixelconnecting line disposed parallel with the data line in the pixel regionand connected to the capacitor electrode; and a pixel electrodedisposing within the circular opening, extending from the pixelconnecting line and including a plurality of pixel electrode patterns;wherein an innermost pixel electrode pattern has a circular shape andthe other pixel electrode patterns are patterned to have circular bands,wherein an innermost portion of the plurality of common electrodepatterns is circular shaped, and wherein the aperture area is circularband shaped.

In another aspect, a method of forming an array substrate for use in anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode, a common electrodeincluding a plurality of common electrode patterns and a common linedisposed parallel to and spaced apart from the gate line on a substratethrough a first mask process, wherein an outermost portion of the commonelectrode pattern has a substantially rectangle and a circular openingin the middle thereof; forming a gate insulating layer on the gate line,the common electrode and the common line; forming a semiconductor layerusing a second mask process on the gate insulating layer and over thegate electrode; forming a data line crossing the gate line to define apixel region having an aperture area, a source electrode extending fromthe data line, and a drain electrode spaced apart from the sourceelectrode using a third mask process, wherein the source and drainelectrodes overlaps opposite end portions of the semiconductor layer,the semiconductor layer being exposed between the source and drainelectrodes, and the gate electrode, the semiconductor layer, the sourceelectrode and the drain electrode constitute a thin film transistor;forming a passivation layer over an entire of the substrate to cover thethin film transistor and then patterning the passivation layer through afourth mask process to form a drain contact hole exposing a portion ofthe drain electrode; and forming a capacitor electrode that overlaps theoutermost portion of the common electrode pattern and connects to thedrain electrode, a pixel connecting line connected to the capacitorelectrode, and a pixel electrode extending from the pixel connectingline and including a plurality of pixel electrode patterns on thepassivation layer through a fifth mask process; wherein an innermostpixel electrode pattern has a circular shape, wherein an innermostportion of the plurality of common electrode patterns and the pluralityof pixel electrode patterns are circular band shaped, wherein theaperture area is circular band shaped.

In another aspect, a method of forming an array substrate for use in anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode, a common electrodeincluding a plurality of common electrode patterns and a common linedisposed parallel to and spaced apart from the gate line on a substratethrough a first mask process, wherein an outermost portion of the commonelectrode pattern is substantially rectangle shaped and has asubstantially circular opening in the middle thereof; forming a gateinsulating layer on the gate line, the common electrode and the commonline; forming a data line crossing the gate line to define a pixelregion having an aperture area, a source electrode extending from thedata line, a drain electrode spaced apart from the source electrodeacross the gate electrode, a semiconductor layer under the data line andhaving the same pattern shape as the data line, a semiconductor layerthat extends from the semiconductor line over the gate electrode andunder the source and drain electrodes using a second mask process,wherein the source and drain electrodes overlap opposite end portions ofthe gate electrode, the semiconductor layer being exposed between thesource and drain electrodes, and the gate electrode, the semiconductorlayer, the source electrode and the drain electrode form a thin filmtransistor; forming a passivation layer over an entire surface of thesubstrate to cover the thin film transistor and then patterning thepassivation layer using a third mask process to form a drain contacthole to expose a portion of the drain electrode; and forming a capacitorelectrode that overlaps the outermost portion of the common electrodepattern and connects to the drain electrode, a pixel connecting lineconnected to the capacitor electrode, and a pixel electrode that extendsfrom the pixel connecting line and includes a plurality of pixelelectrode patterns on the passivation layer using a fourth mask process;wherein an innermost pixel electrode pattern has a circular shape,wherein an innermost portion of the plurality of common electrodepatterns and the plurality of pixel electrode patterns are circular bandshaped, and wherein the aperture are is circular band shaped.

In another aspect, an array substrate for use in an in-plane switchingliquid crystal display device is provided. The array substrate includesa gate line on a substrate; a data line crossing the gate line to definea pixel region having an aperture area; a thin film transistor disposedat one corner of the pixel region and connected to the gate line and thedata line, the thin film transistor including a semiconductor layer; acommon electrode disposing in the pixel region and having first andsecond common electrode patterns, wherein the first common electrodepattern is substantially rectangle shaped and has a substantiallycircular opening in the middle thereof, and the second common electrodepattern is disposed in the circular opening and has a gyre shape; acommon line substantially perpendicular to and crossing the data lineand connecting the common electrode to a neighboring common electrode ina neighboring pixel region; a capacitor electrode overlapping the firstcommon electrode pattern, the capacitor electrode connected to the thinfilm transistor; a pixel electrode disposed within the substantiallycircular opening and having a gyre shape along a side of the secondcommon electrode pattern, wherein the pixel electrode and the secondcommon electrode pattern each have the substantially gyre shape; andwherein the aperture area is substantially gyre shaped.

In another aspect, a method of forming an array substrate for anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode, a common electrodehaving first and second common electrode patterns, and a common linedisposed parallel to and spaced apart from the gate line on a substrateusing a first mask process, wherein the first common electrode patternis substantially rectangle shaped and has a substantially circularopening in the middle thereof, and the second common electrode patternis disposed in the substantially circular opening and has asubstantially gyre shape; forming a gate insulating layer on the gateline, the common electrode and the common line; forming a semiconductorlayer on the gate insulating layer and over the gate electrode using asecond mask process; forming a data line that crosses the gate line todefine a pixel region having an aperture area, a source electrodeextending from the data line, and a drain electrode spaced apart fromthe source electrode using a third mask process, wherein the source anddrain electrodes overlap opposite end portions of the semiconductorlayer, the semiconductor layer being exposed between the source anddrain electrodes, and the gate electrode, the semiconductor layer, thesource electrode and the drain electrode form a thin film transistor;forming a passivation layer over an entire surface of the substrate tocover the thin film transistor and patterning the passivation layerusing a fourth mask process to form a drain contact hole to expose aportion of the drain electrode; and forming a capacitor electrodeoverlapping the first common electrode pattern, and a pixel electrodewithin the substantially circular opening and having a substantiallygyre shape along a side of the second common electrode pattern using afifth mask process, wherein the capacitor electrode is connected to thethin film transistor, and the pixel electrode and the second commonelectrode pattern each have the substantially gyre shape, wherein theaperture area is substantially gyre shape.

In another aspect, a method of forming an array substrate for anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode, a common electrodehaving first and second common electrode patterns, and a common linedisposed substantially parallel to and spaced apart from the gate lineon a substrate using a first mask process, wherein the first commonelectrode pattern is substantially rectangle and has a substantiallycircular opening in the middle thereof, and the second common electrodepattern is disposed in the substantially circular opening and has asubstantially gyre shape; forming a gate insulating layer on the gateline, the common electrode and the common line; forming a data line thatcrosses the gate line to define a pixel region having an aperture area,a source electrode extending from the data line, a drain electrodespaced apart from the source electrode across the gate electrode, asemiconductor layer under the data line and having the same patternshape as the data line, and a semiconductor layer extending from thesemiconductor line over the gate electrode and under the source anddrain electrode using a second mask process, wherein the source anddrain electrodes overlap opposite end portions of the gate electrode,the semiconductor layer being exposed between the source and drainelectrodes, and the gate electrode, the semiconductor layer, the sourceelectrode and the drain electrode forming a thin film transistor;forming a passivation layer over an entire surface of the substrate tocover the thin film transistor and patterning the passivation layerusing a third mask process to form a drain contact hole to expose aportion of the drain electrode; and forming a capacitor electrodeoverlapping the first common electrode pattern, and a pixel electrodedisposing within the substantially circular opening and having asubstantially gyre shape along the second common electrode pattern usinga fourth mask process, wherein the capacitor electrode is connected tothe thin film transistor, and the pixel electrode and the second commonelectrode pattern each have the substantially gyre shape, wherein theaperture area is substantially gyre shape.

In another aspect, an array substrate for an in-plane switching liquidcrystal display device is provided. The array substrate includes a gateline on a substrate; a data line crossing the gate line to define apixel region having an aperture area; a semiconductor line under thedata line and having the same pattern shape as the data line; a thinfilm transistor disposed at one corner of the pixel region and connectedto the gate and data lines, the thin film transistor including sourceand drain electrodes and a semiconductor layer extending from thesemiconductor line; a common line spaced apart from and substantiallyparallel to the gate line; a common electrode extending from the commonline and including a plurality of common electrode patterns, wherein anoutermost common electrode pattern is substantially rectangle within thepixel region and has a substantially circular opening in the middlethereof; a capacitor electrode overlapping a previous gate line of apreviously neighboring pixel region; a pixel electrode within thesubstantially circular opening and including a plurality of pixelelectrode patterns; and a pixel connecting line substantially parallelto the data line in the pixel region and connected to the capacitorelectrode, the pixel electrode and the drain electrode of the thin filmtransistor; wherein the pixel electrode overlaps portions of the pixelconnecting line and directly contacts the pixel connecting line; whereinan innermost pixel electrode pattern has a substantially circular shapeand other pixel electrode patterns are patterned to have circular bands,and wherein the plurality an innermost portion of the common electrodepatterns is substantially circular band shaped, and wherein the aperturearea is circular band shaped.

In anther aspect, a method of forming an array substrate for use in anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode, a common electrodeincluding a plurality of common electrode patterns, and a common linesubstantially parallel to and spaced apart from the gate line on asubstrate using a first mask process, wherein an outermost commonelectrode pattern is substantially rectangle shaped and has asubstantially circular opening in the middle thereof; forming a gateinsulating layer on the gate line, the common electrode and the commonline; forming a data line crossing the gate line to define a pixelregion having an aperture area, a source electrode extending from thedata line, a drain electrode spaced apart from the source electrodeacross the gate electrode, a pixel connecting line extending from thedrain electrode and substantially parallel to the data line, a capacitorelectrode over a previous gate line with extending from the pixelconnecting line, a semiconductor line under the data line and having thesame pattern shape as the data line, and a semiconductor layer extendingfrom the semiconductor line over the gate electrode and under the sourceand drain electrode using a second mask process, wherein the source anddrain electrodes overlap opposite end portions of the gate electrode,the semiconductor layer being exposed between the source and drainelectrodes, and the gate electrode, the semiconductor layer, the sourceelectrode and the drain electrode forming a thin film transistor;forming a photoresist pattern on the thin film transistor using a thirdmask process, the photoresist pattern having openings between theplurality of common electrode patterns; forming a transparent conductivelayer on an entire surface of the substrate to cover the photoresistpattern; and removing the transparent conductive layer on thephotoresist pattern by stripping the photoresist pattern to obtain apixel electrode, wherein the pixel electrode fits in the openings of thephotoresist and directly contacts the pixel connecting line andincluding a plurality of pixel electrode patterns, wherein an innermostpixel electrode pattern has a substantially circular shape and otherpixel electrode patterns are patterned to have circular bands, whereinan innermost portion of the plurality of common electrode patterns issubstantially circular band shaped, and wherein the aperture area iscircular band shaped.

In another aspect, an array substrate for use in an in-plane switchingliquid crystal display device is provided. The array substrate includesa gate line on a substrate; a data line crossing the gate line to definea pixel region having an aperture area; a semiconductor line under thedata line and having the same pattern shape as the data line; a thinfilm transistor disposed at one corner of the pixel region and connectedto the gate and data lines, the thin film transistor including sourceand drain electrodes and a semiconductor layer extending from thesemiconductor line; a common line spaced apart from and substantiallyparallel to the gate line; a capacitor electrode overlapping a previousgate line of a previously neighboring pixel region; a pixel connectingline substantially parallel to the data line within the pixel region andconnected to the capacitor electrode and the drain electrode of the thinfilm transistor; a common electrode including a plurality of commonelectrode patterns, each of common electrode patterns divided into twoparts by the pixel connecting line without overlapping the pixelconnecting line; and a pixel electrode within the substantially circularopening and including a plurality of pixel electrode patterns withoutoverlapping the common line, wherein an outermost common electrodepattern is substantially rectangle shaped within the pixel region andhas a substantially circular opening in the middle thereof, and othercommon electrode patterns are shaped substantially like semicirculararcs, wherein an innermost pixel electrode pattern has a rod shape andis disposed within an area of pixel connecting line, and the other pixelelectrode patterns have a substantially semicircular-arc shape; andwherein the plurality of common electrode patterns the plurality ofpixel electrode patterns form substantially circular band shapedaperture area.

In another aspect, a method of forming an array substrate for use in anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode and a common linesubstantially parallel to and spaced apart from the gate line on asubstrate using a first mask process; forming a gate insulating layer onthe gate line and the common line; forming a data line that crosses thegate line to define a pixel region having an aperture area, a sourceelectrode extending from the data line, a drain electrode spaced apartfrom the source electrode across the gate electrode, a pixel connectingline extending from the drain electrode and substantially parallel tothe data line, a capacitor electrode over a previous gate line extendingfrom the pixel connecting line, a semiconductor line under the data lineand having the same pattern shape as the data line, and a semiconductorlayer extending from the semiconductor line over the gate electrode andunder the source and drain electrode using a second mask process,wherein the source and drain electrodes overlap opposite end portions ofthe gate electrode, the semiconductor layer being exposed between thesource and drain electrodes, and the gate electrode, the semiconductorlayer, the source electrode and the drain electrode forming a thin filmtransistor; forming a photoresist pattern on the thin film transistorusing a third mask process, the photoresist pattern including first twosymmetric open portions separated from the pixel connecting line withoutoverlapping the pixel connecting line and second two symmetric openportions separated from the common line without overlapping the commonline; etching the gate insulating layer using the photoresist pattern asan etch mask to expose the common and pixel connecting lines under thefirst two symmetric open portions; forming a transparent conductivelayer on an entire surface of the substrate having the photoresistpattern; and removing the transparent conductive layer on thephotoresist pattern by stripping the photoresist pattern to obtain acommon electrode and a pixel electrode, wherein the common and pixelelectrodes fit in the first and second symmetric open portions of thephotoresist, the common electrode including a plurality of commonelectrode patterns, and the pixel electrode including a plurality ofpixel electrode patterns, wherein an outermost common electrode patternis substantially rectangle shaped within the pixel region and has asubstantially circular opening in the middle thereof, and other commonelectrode patterns are patterned to have substantially semicirculararcs, wherein an innermost pixel electrode pattern has a rod shape andis disposed within an area of pixel connecting line, and the other pixelelectrode patterns are substantially semicircular-arc shaped, andwherein the aperture area is circular band shaped.

In another aspect, an array substrate for use in an in-plane switchingliquid crystal display device is provided. The array substrate a gateline on a substrate; a data line crossing the gate line to define apixel region having an aperture area; a thin film transistor disposed atone corner of the pixel region and connected to the gate line and thedata line, the thin film transistor including a gate electrode, asemiconductor layer and source and drain electrodes; a common linespaced apart and substantially parallel to the gate line; a commonelectrode extending from the common line and including a plurality ofcommon electrode patterns, wherein an outermost common electrode patternis substantially rectangle shaped within the pixel region and has asubstantially rectangular opening in the middle thereof; a capacitorelectrode overlapping the substantially rectangular common electrodepattern, the capacitor electrode connected to the thin film transistor;a pixel connecting line substantially parallel to the data line in thepixel region and connected to the capacitor electrode; and a pixelelectrode within the substantially rectangular opening, extending fromthe pixel connecting line and including a plurality of pixel electrodepatterns, wherein an innermost pixel electrode pattern has asubstantially circular shape and other pixel electrode patterns arepatterned to have circular bands, wherein an innermost portion of theplurality of common electrode patterns is circular band shaped, andwherein the aperture area is circular band shaped.

In another aspect, an array substrate for use in an in-plane liquidcrystal display device is provided. The array substrate includes a gateline on a substrate; a data line crossing the gate line to define apixel region; a semiconductor line under the data line and having thesame pattern shape as the data line; a thin film transistor disposed atone corner of the pixel region and connected to the gate and data lines,the thin film transistor including source a gate electrode, and drainelectrodes and a semiconductor layer extending from the semiconductorline; a common line spaced apart from and substantially parallel to thegate line; a capacitor electrode overlapping a previous gate line of apreviously neighboring pixel region; a pixel connecting linesubstantially parallel to the data line in the pixel region, extendingfrom the drain electrode, and connecting the capacitor electrode and thedrain electrode of the thin film transistor; a passivation layer overthe thin capacitor and pixel electrodes, the passivation layer havingfirst and second contact holes that expose the common line and pixelconnecting line, respectively; a common electrode on the passivationlayer and having a plurality of common electrode patterns, wherein anoutermost common electrode pattern is continuously connected toneighboring outermost common electrode patterns of neighboring pixelregions and has a substantially circular opening in the middle of thepixel region, and other common electrode patterns have circular bandshapes; and a pixel electrode disposing within the substantiallycircular opening and including a plurality of pixel electrode patterns,wherein an innermost pixel electrode pattern has a substantiallycircular shape and is disposed over a crossing of the common and pixelconnecting lines, and the other pixel electrode patterns have circularband shapes.

In another aspect, an array substrate for an in-plane switching liquidcrystal display device is provided. The array substrate includes a gateline on a substrate; a data line crossing the gate line to define apixel region having an aperture area; a gate pad connected to one end ofthe gate line; a data pad connected to one end of the data line; a gatepad terminal connected to the gate pad; a data pad terminal connected tothe data pad; a semiconductor line under the data line and having thesame pattern shape as the data line; a thin film transistor disposed atone corner of the pixel region and connected to the gate and data lines,the thin film transistor including source and drain electrodes and asemiconductor layer extending from the semiconductor line; a common linespaced apart from and substantially parallel to the gate line; a commonelectrode extending from the common line and including a plurality ofcommon electrode patterns, wherein an outermost common electrode patternis substantially rectangle-shaped within the pixel region and has asubstantially circular opening in the middle thereof; a capacitorelectrode overlapping a previous gate line of a previously neighboringpixel region; a pixel electrode within the substantially circularopening and including a plurality of pixel electrode patterns; and apixel connecting line substantially parallel to the data line in thepixel region and connected to the capacitor electrode, the pixelelectrode and the drain electrode of the thin film transistor, whereinthe innermost pixel electrode pattern is shaped like a rod and disposedwithin an area of the pixel connecting line, wherein the pixel electrodeoverlaps portions of the pixel connecting line and directly contacts thepixel connecting line, wherein other pixel electrode patterns arepatterned to have semicircular shapes, and wherein the semiconductorline extends underneath the source and drain electrodes, the pixelconnection line and the capacitor electrode, wherein an innermostportion of the plurality of common electrode patterns is substantiallycircular band shaped, and wherein the aperture area is circular bandshaped.

In another aspect, a method of forming an array substrate for use in anin-plane switching liquid crystal display device is provided. The methodincludes forming a gate line having a gate electrode, a common electrodeincluding a plurality of common electrode patterns, a gate pad connectedto one end of the gate line and a common line substantially parallel toand spaced apart from the gate line on a substrate using a first maskprocess, wherein an outermost common electrode pattern is substantiallyrectangle-shaped and has a substantially circular opening in the middlethereof; forming a gate insulating layer on the gate line, the commonelectrode, the gate pad and the common line; forming a data line thatcrosses the gate line to define a pixel region having an aperture area,a source electrode extending from the data line, a drain electrodespaced apart from the source electrode across the gate electrode, apixel connecting line extending from the drain electrode andsubstantially parallel to the data line, a capacitor electrode over aprevious gate line with extending from the pixel connecting line, a datapad connected to one end of the data line, a semiconductor line underthe data line and having the same pattern shape with the data line, anda semiconductor layer extending from the semiconductor line over thegate electrode and under the source and drain electrodes and pixelconnecting line and capacitor electrode using a second mask process,wherein the source and drain electrodes overlap opposite end portions ofthe gate electrode, the semiconductor layer being exposed between thesource and drain electrodes, and the gate electrode, the semiconductorlayer, the source electrode and the drain electrode form a thin filmtransistor; forming a passivation layer over the data line, the sourceand drain electrodes, the data pad, the pixel connecting line, and thecapacitor electrode; forming a photoresist pattern on the passivationlayer to cover the thin film transistor using a third mask process, thephotoresist pattern having openings between the plurality of commonelectrode patterns and contact openings exposing the gate and data pads;forming a transparent conductive layer on an entire surface of thesubstrate to cover the photoresist pattern; and removing the transparentconductive layer on the photoresist pattern by stripping the photoresistpattern to obtain a pixel electrode, a gate pad terminal and a data padterminal, wherein the pixel electrode fits in the openings of thephotoresist and directly contacts the pixel connecting line, the pixelelectrode including a plurality of pixel electrode patterns, wherein aninnermost pixel electrode pattern has a substantially rod shape andother pixel electrode patterns are patterned to have semicircularshapes, wherein an innermost portion of the plurality of commonelectrode patterns is substantially circular band shaped, and whereinthe aperture area is circular band shaped.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the presentinvention and together with the description serve to explain theprinciples of that invention.

In the drawings:

FIG. 1 is a schematic cross-sectional view illustrating a related artIPS-LCD panel;

FIG. 2 is a plan view illustrating a pixel of an array substrateaccording to a related art IPS-LCD device;

FIG. 3 is a plan view of an array substrate for use in an IPS-LCD devicehaving multiple domains according to the related art;

FIG. 4 is a graph illustrating a viewing angle of the IPS-LCD devicehaving the zigzag structure of FIG. 3;

FIG. 5 is a plan view illustrating a pixel of an array substrate for usein an IPS-LCD device according a first embodiment of the presentinvention;

FIGS. 6A-6E are plan views illustrating process steps of forming thearray substrate of FIG. 5;

FIG. 7 is a schematic plan view of an array substrate for an IPS-LCDdevice according to a second embodiment of the present invention;

FIGS. 8A-8E are schematic plane views illustrating a five-mask processfor fabricating the array substrate of FIG. 7;

FIG. 9 is a plan view illustrating a pixel of an array substrate for usein an IPS-LCD device according a third embodiment of the presentinvention;

FIGS. 10A-10D are plan views illustrating process steps of forming thearray substrate of FIG. 9;

FIG. 11 is a schematic plan view of an array substrate for an IPS-LCDdevice according to a fourth embodiment of the present invention;

FIGS. 12A-12D are schematic plane views illustrating a four-mask processfor fabricating the array substrate of FIG. 11;

FIGS. 13A-13D are cross sectional views illustrating a lift-off process;

FIG. 14 is a plan view illustrating an array substrate for use in anIPS-LCD device according to a fifth embodiment of the present invention;

FIGS. 15A to 15D are schematic plane views illustrating a three maskprocess of fabricating an array substrate for an IPS-LCD deviceaccording to a fifth embodiment of the present invention;

FIG. 16 is a plan view of an array substrate for use in an IPS-LCDdevice according to a sixth embodiment of the present invention;

FIGS. 17A to 17D are schematic plan views illustrating a three-maskprocess for fabricating the array substrate of FIG. 16;

FIG. 18 show simulation testing results of gray level and liquid crystaldirector conducting on the IPS-LCD device of the present inventiondepending on the applied voltages;

FIG. 19 is a schematic plane view of an array substrate for an IPS-LCDdevice according to a seventh embodiment of the present invention;

FIG. 20 is a schematic plan view illustrating a pixel of an arraysubstrate for use in an IPS-LCD device according an eighth embodiment ofthe present invention;

FIG. 21 is a schematic plane view of an array substrate for an IPS-LCDdevice according to a ninth embodiment of the present invention;

FIG. 22 is a schematic plan view illustrating a pixel of a color filtersubstrate that is attached to the aforementioned array substrate;

FIG. 23 is a plan view illustrating a pixel of an array substrate foruse in an IPS-LCD device according to a tenth embodiment of the presentinvention;

FIG. 24 is a schematic plan view of an array substrate for an IPS-LCDdevice according to an eleventh embodiment of the present invention;

FIGS. 25A-25D are cross sectional views illustrating the process stepsof forming the gate pad of FIG. 14; and

FIGS. 26A-26D are cross sectional views illustrating the process stepsof forming the data pad of FIG. 14.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to illustrated embodiments of thepresent invention, examples of which are shown in the accompanyingdrawings. Wherever possible, similar reference numbers will be usedthroughout the drawings to refer to the same or similar parts.

FIG. 5 is a plan view illustrating a pixel of an array substrate for usein an IPS-LCD device according a first embodiment of the presentinvention. In this embodiment, the common and pixel electrodes have acircular shape, and the array substrate is fabricated using a five-maskprocess.

As shown in FIG. 5, a gate line 112 is transversely arranged and a dataline 128 is disposed substantially perpendicular to the gate line 112. Apair of gate and data lines 112 and 128 define one pixel region P on asubstrate 110, and common and pixel electrodes 120 and 138,respectively, both having circular shapes, are formed within the pixelregion P. Because the pixel electrode 138 and the common electrode 120have the circular shapes, liquid crystal detectors are the same in alldirections and color inversion along a specific angle is prevented. Athin film transistor (TFT) T is disposed near a crossing of the gate anddata lines 112 and 128, respectively. A common line 114 runs from leftto right in the middle of the pixel region P and is substantiallyparallel with and spaced apart from the gate line 112.

The common electrode 120 includes a firs common electrode pattern 120 athat surrounds the pixel region P and has a circular opening 118 in themiddle, and a second common electrode pattern 120 b within the circularopening 118. First, half portions of the first and second commonelectrode patterns 120 a and 120 b extend from the common line 114 in anupward direction, and second half portions extend from the common line114 in a downward direction. Thus, the first and second common electrodepatterns 120 a and 120 b are connected to the common line 114. The firstcommon electrode pattern 120 a is shaped like a rectangle and has thecircular opening 118 therein, while the second common electrode pattern120 b is shaped like a ring. Because the common line 114 transverselycrosses the pixel region P, the common line 114 corresponds to andcrosses along a diametric line of the circular band shaped second commonelectrode pattern 120 b and the circular opening 118.

A capacitor electrode 140 is formed in an area where the first commonelectrode pattern 120 a is disposed such that the capacitor electrode140 overlaps the first common electrode pattern 120 a and forms astorage capacitor “CST” with the overlapped portions of the first commonelectrode pattern 120 a. The capacitor electrode 140 includes a firstcapacitor electrode pattern 140 a and a second capacitor electrodepattern 140 b, respectively, in bottom and top portions of the pixelregion P. The first capacitor electrode pattern 140 a is connected tothe second capacitor electrode pattern 140 b through a pixel connectingline 141, and the first capacitor electrode pattern 140 a is connectedto the TFT T.

The pixel electrode 138 includes first and second pixel electrodepatterns 138 a and 138 b. The first pixel electrode pattern 138 a has aring shape and is disposed between the first and second common electrodepatterns 120 a and 120 b, and the second pixel electrode pattern 138 bhas a circular shape is disposed inside the circular band shaped secondcommon electrode pattern 120 b. The pixel connecting line 141 isvertically disposed in the middle of the pixel region P and connects thefirst and second capacitor electrode patterns 140 a and 140 b to eachother. Furthermore, the pixel connecting line 141 also connects thefirst pixel electrode pattern 138 a to the second pixel electrodepattern 138 b. Accordingly, the pixel electrode 138, the capacitorelectrode 140 and the pixel connecting line 141 may form as one unitedor integrated body during the same patterning process.

In the first embodiment illustrated with reference to FIG. 5, the pixelregion P may be divided into multi domains, e.g., four domains, by thepixel connecting line 141 and the common line 114. To prevent reductionof a lateral electric field between the first common electrode pattern120 a and the first pixel electrode pattern 138 a, the capacitorelectrode 140 may be formed to have a smaller area than the first commonelectrode pattern 120 a and expose edge portions of the first commonelectrode pattern 120 a. Moreover, since aperture areas defined betweenthe common and pixel electrodes 120 and 138 have circular shapes, theliquid crystal directors become the same in all directions. Thus, thecolor shift is provided that would have occurred in ±45 directions ofthe related art. Furthermore, the image quality of the IPS-LCD device isimproved, and the IPS-LCD device has much wider viewing angle.

FIGS. 6A-6E are plan views illustrating process steps of forming thearray substrate of FIG. 5. In this embodiment, the fabrication iscompleted using a five-mask process.

In FIG. 6A, a first metal layer is formed on the substrate 110 and thenpatterned in a first mask process to form a gate electrode 116, the gateline 112, the common line 114, the common electrode 120 and the circularopening 118. As described with reference to FIG. 5, the gate line 112and the common line 114 are transversely disposed. The gate electrode116 extends from the gate line 112, and the common electrode 120 extendsfrom the common line 114 in both up and down directions. The commonelectrode 120 includes the first and second common electrode patterns120 a and 120 b. The first common electrode pattern 120 a includes thecircular opening 118 therein. Also, the first common electrode pattern120 a is shaped like a rectangle within the pixel region P such that itsurrounds a boundary portion of the pixel region P. The second commonelectrode pattern 120 b has a ring shape and is disposed within thecircular opening 118. The common line 114 crosses the pixel region P inthe middle such that it runs along the diametric line of the circularband shaped second common electrode pattern 120 b and the circularopening 118.

In FIG. 6B, after forming a gate insulating layer (not shown) over thesubstrate 110 to cover the gate line 112, the common line 114 and thecommon electrode 120, a semiconductor layer 126 is formed on the gateinsulating layer by a second mask process, including the gate electrode116. Although not shown in FIG. 6B, the semiconductor layer 126 mayinclude first layer of pure amorphous silicon and a second layer ofdoped amorphous silicon.

FIG. 6C illustrates a step of forming the data line 128 using a thirdmask process. A second metal layer is formed over the substrate 110 andthen patterned to form the data line 128 and source and drain electrodes130 and 132. The data line 128 is perpendicular to the gate line 112.The source electrode 130 extends from the data line 128 over one portionof the semiconductor layer 126, and the drain electrode 132 is spacedapart from the source electrode 130 and overlaps the other portion ofthe semiconductor layer 126. After forming the source and drainelectrode 130 and 132, a channel “ch” is formed on the semiconductorlayer 126. The gate electrode 116, the semiconductor layer 126 and thesource and drain electrodes 130 and 132 form a thin film transistor(TFT) T.

In FIG. 6D, a passivation layer (not shown) having a drain contact hole134 is formed on the TFT T through a fourth mask process. The draincontact hole 134 exposes the drain electrode 132.

FIG. 6E illustrates a fifth mask process in which the pixel electrode138 is formed. A transparent conductive layer is formed on thepassivation layer having the drain contact hole 134, and then patternedby the fifth mask process. Thus, the pixel electrode 138, the capacitorelectrode 140 and the pixel connecting line 141 on the passivationlayer. The pixel electrode 138 includes first and second pixel electrodepatterns 138 a and 138 b. The first pixel electrode pattern 138 a isshaped like a ring and disposed between the first and second commonelectrode patterns 120 a and 120 b. The second pixel electrode pattern138 b is shaped like a circle and disposed inside the second commonelectrode pattern 120 b in the middle of the pixel region P. Thecapacitor electrode 140 includes the first and second capacitorelectrode patterns 140 a and 140 b which are disposed over top andbottom portions of the first common electrode pattern 120 a,respectively. The pixel connecting line 141 is vertically disposed inthe pixel region P, crosses the common line, and is connected to thefirst and second capacitor electrode patterns 140 a and 140 b. The pixelconnecting line 141 also connects the first and second pixel electrodepatterns 138 a and 138 b to each other. The pixel connecting line 141may be formed as a unitary pattern with the pixel electrode 138 and thecapacitor electrode 140 through one process.

The pixel region P may be divided into four sections by the common line114 and pixel connecting line 141, such that the four sections form amulti-domain structure. Specifically, the pixel region P is comprised offour domains, for example. Because the common and pixel electrodes 120and 140 form circular aperture areas between the respective commonelectrode patterns and the respective pixel electrode patterns, theliquid crystal directors are the same in all directions. Thus, colorshift and contrast degradation are prevented.

The transparent conductive layer for the pixel electrode 140 may be oneof indium tin oxide (ITO), indium tin zinc oxide (ITZO) and indium zincoxide (IZO).

FIG. 7 is a schematic plan view of an array substrate for an IPS-LCDdevice according to a second embodiment of the present invention. Inthis second embodiment, the array substrate has an aperture area havinga gyroidal shape defined by gyroidal common and pixel electrodes.

In FIG. 7, a gate line 212 is transversely arranged and a data line 228is arranged substantially perpendicular to the gate line 212. A pixelregion P is defined on the array substrate by a crossing of the gate anddata lines 212 and 228. A thin film transistor (TFT) T is arranged inthe pixel region P near a crossing of the gate and data line 212 and228.

Within the pixel region P, a first common electrode pattern 220 a havinga rectangular shape is located. The first common electrode pattern 220 ahas a circular opening 218 in the middle thereof such that the firstcommon electrode pattern 220 a surrounds a boundary portion of the pixelregion P. A second common electrode pattern 220 b, having a gyre shape,is located in the circular opening 218 as an extension from the firstcommon electrode pattern 220 a. The first and second common electrodepatterns 220 a and 220 b form a common electrode 220. A common line 214crosses the data line 228 and connects the common electrode 220 to aneighboring common electrode (not shown) in a neighboring pixel region.The common line 214 may be formed as one united or integral body withthe common electrode 220.

A capacitor electrode 240 is formed to overlap the first commonelectrode pattern 220 a and forms a storage capacitor “CST” with theoverlapped portions of the first common electrode pattern 220 a. One endof the capacitor electrode 240 is connected to a drain electrode 232 ofthe TFT T. A pixel electrode 238 having a gyre shape is also disposed inthe circular opening 218. The gyroidal pixel electrode 238 extendsbeginning from the capacitor electrode 240 alongside the gyroidal firstcommon electrode pattern 220 a. The first helical turn of the gyroidalpixel electrode 238 should be disposed between the first helical turn ofthe gyroidal second common electrode pattern 220 b and the first commonelectrode pattern 220 a in order to form a gyre-shaped aperture areabetween the common and pixel electrodes 220 and 238. The pixel electrode238 may be shaped to surround and be spaced apart from the second commonelectrode pattern 220 b. In the second embodiment illustrated withreference to FIG. 7, the capacitor electrode 240 may be formed to have asmaller width than the first common electrode pattern 220 a and expose aboundary portion of the first common electrode pattern 220 a to generatea lateral electric field between the first common electrode pattern 220a and the pixel electrode 238.

FIGS. 8A-8E are schematic plan views illustrating a five-mask processfor fabricating the array substrate of FIG. 7.

In FIG. 8A, a first metal layer is formed on the substrate 210 and thenpattern through a first mask process to form the gate line 212, thecommon line 214, and the common electrode 220 including first and secondcommon electrode patterns 220 a and 220 b. A gate electrode 216extending from the gate line 212 is also formed. The common line 214connects the common electrode 220 to a neighboring common electrode (notshown) of the next pixel region. The first common electrode pattern 220a may be shaped like a rectangle and includes a circular opening 218therein such that the first common electrode pattern 220 a overlapsperipheral portions of a pixel region P. The second common electrodepattern 220 b has a gyre shape and extends from the first commonelectrode pattern 220 a in the circular opening 218.

In FIG. 8B, after patterning the first metal layer, a gate insulatinglayer (not shown) is formed over an entire surface of the substrate 210to cover the gate line 212 and the common electrode 220. Then, asemiconductor layer 226 is formed, through a second mask process, on thegate insulating layer (not shown), and the gate electrode 216. Thesemiconductor layer 226 may be a double layer including a first layer ofpure amorphous silicon and a second layer of doped amorphous silicon.

In FIG. 8C, a second metal layer is formed over the entire surface ofthe substrate 210 to cover the semiconductor layer 226, and thenpatterned, through a third mask process, to form the data line 228substantially perpendicular to the gate line 212. The source and drainelectrodes 230 and 232 are also formed to contact the semiconductorlayer 226. The source electrode 230 extends from the data line 228 overone portion of the semiconductor layer 226, and the drain electrode 232is spaced apart from the source electrode 230 across the gate electrode216. The doped amorphous silicon exposed between the source and drainelectrodes 230 and 232 is etched to form a channel “ch” on thesemiconductor layer 226. The gate electrode 216, the semiconductor layer226 and the source and drain electrodes 230 and 232 form a thin filmtransistor T.

FIG. 8D illustrates formation of a drain contact hole 234. A passivationlayer (not shown) is formed over the entire surface of the substrate 210to cover the thin film transistor T. Then, the passivation layer (notshown) is patterned, through a fourth mask process, to form the draincontact hole 234 to expose a portion of the drain electrode 232.

In FIG. 8E, a transparent conductive layer is formed on the passivationlayer having the drain contact hole 234, and then patterned, through afifth mask process, to form the capacitor electrode 240 and thegyre-shaped pixel electrode 238. The capacitor electrode 240 may bearrayed to overlap the first common electrode pattern 220 a and beconnected to the drain electrode 232 through the drain contact hole 234.The pixel electrode 238, having a gyre shape, extends from the capacitorelectrode 240 alongside the gyroidal second common electrode pattern 220b. The extension of the pixel electrode 238 from the capacitor electrode240 starts from a portion next to the beginning of the gyre-shapedsecond common electrode pattern 220 b. The capacitor electrode 240 mayhave a smaller width than the first common electrode pattern 220 a toprevent electrical interruption between the pixel electrode 238 and thecapacitor electrode 240.

FIG. 9 is a plan view illustrating one pixel of an array substrate foruse in an IPS-LCD device according a third embodiment of the presentinvention. The array substrate of FIG. 9 is very similar to that of FIG.5, except the array substrate is completed using a four-mask process inwhich diffraction exposure is utilized to form the semiconductor layerand the data line.

As shown in FIG. 9, a gate line 312 is transversely arranged and a dataline 328 is disposed substantially perpendicular to the gate line 312. Apair of gate and data lines 312 and 328 define one pixel region P on asubstrate 310, and common and pixel electrodes 320 and 338 both, havingcircular shapes, are formed within the pixel region P. Because the pixelelectrode 338 and the common electrode 320 have circular shapes, liquidcrystal detectors are the same in all directions and a color inversionalong a specific angle is prevented. A common line 314 runs from left toright in the middle of the pixel region P. The common line issubstantially parallel with and spaced apart from the gate line 312. Athin film transistor (TFT) T is disposed near a crossing of the gate anddata lines 312 and 328. The TFT T includes a gate electrode 316, asemiconductor layer 326, a source electrode 330 and a drain electrode332. The gate electrode 316 extends from the gate line 312, and thesource electrode 330 extends from the data line 328. The drain electrode332 is spaced apart from the source electrode 330 and overlaps a portionof the gate electrode 316. The data line 328 and the source and drainelectrodes 320 and 332 are formed with the semiconductor layer 326during the same patterning process such that a semiconductor line 325 isdisposed under the data line 328 and has the same pattern shape as thedata line 328. Specifically, the semiconductor layer 326 extends fromthe semiconductor line 325 and is also disposed under the source anddrain electrodes 330 and 332.

As illustrated in FIG. 5, the common electrode 320 includes a firscommon electrode pattern 320 a that surrounds the pixel region P and hasa circular opening 318 in the middle, and a second common electrodepattern 320 b within the circular opening 318. Portions of a first halfof the first and second common electrode patterns 320 a and 320 b extendfrom the common line 314 in an upward direction, and portions of asecond half extend in a downward direction from common line 314. Thus,the first and second common electrode patterns 320 a and 320 b areconnected to the common line 114. The first common electrode pattern 320a is shaped like a rectangle and has the circular opening 318, while thesecond common electrode pattern 320 b is shaped like a ring. Because thecommon line 314 transversely crosses the pixel region P, the common line314 corresponds to and crosses along a diametric line of the circularband shaped second common electrode pattern 320 b and the circularopening 318.

A capacitor electrode 340 is formed in an area where the first commonelectrode pattern 320 a is disposed such that the capacitor electrode340 overlaps the first common electrode pattern 320 a and forms astorage capacitor with the overlapped portions of the first commonelectrode pattern 320 a. The capacitor electrode 340 includes a firstcapacitor electrode pattern 340 a and a second capacitor electrodepattern 340 b, respectively, in bottom and top portions of the pixelregion P. The first capacitor electrode pattern 340 a is connected tothe second capacitor electrode pattern 340 b through a pixel connectingline 341, and the first capacitor electrode pattern 340 a is connectedto the TFT T.

The pixel electrode 338 includes first and second pixel electrodepatterns 338 a and 338 b. The first pixel electrode pattern 338 a has aring shape and is disposed between the first and second common electrodepatterns 320 a and 320 b, and the second pixel electrode pattern 338 bhas a circular shape and is disposed inside the circular band shapedsecond common electrode pattern 320 b. The pixel connecting line 341 isvertically disposed in the middle of the pixel region P and connects thefirst and second capacitor electrode patterns 340 a and 340 b to eachother. Furthermore, the pixel connecting line 341 also connects thefirst pixel electrode pattern 338 a to the second pixel electrodepattern 338 b. Accordingly, the pixel electrode 338, the capacitorelectrode 340 and the pixel connecting line 341 may be formed as oneunited or integrated body during the same patterning process.

In the third embodiment illustrated with reference to FIG. 9, the pixelregion P may be divided into multidomains, e.g., four domains, by thepixel connecting line 341 and the common line 314. Moreover, theaperture areas defined between the common and pixel electrodes 320 and338, respectively, have circular shapes similar to the first embodimentof FIG. 5. As a result, color shift is prevented and the image qualityand viewing angle of the IPS-LCD device are improved.

FIGS. 10A-10D are plan views illustrating process steps of forming thearray substrate of FIG. 9. In this embodiment, the fabrication iscompleted using a four-mask process.

In FIG. 10A, a first metal layer is formed on the substrate 110 and thenpatterned in a first mask process to form the gate electrode 316, thegate line 312, the common line 314, the common electrode 320 and thecircular opening 318. As described with reference to FIG. 9, the gateline 312 and the common line 314 are transversely disposed. The gateelectrode 316 extends from the gate line 312. The common electrode 320includes the first and second common electrode patterns 320 a and 320 b,and first half portions of the first and second common electrodepatterns 320 a and 320 b extend from the common line 314 in an upwarddirection and second half portions of the first and second commonelectrode patterns 320 a and 320 b extend in a downward direction. Thefirst common electrode pattern 320 a is shaped like a rectangle withinthe pixel region P and includes a circular opening 318 such that thefirst common electrode pattern 320 a surrounds a boundary portion of thepixel region P. The second common electrode pattern 320 b has a ringshape and is disposed within the circular opening 318. The common line314 horizontally crosses the pixel region P in the middle such that itruns along the diametric line of the circular band shaped second commonelectrode pattern 320 b and the circular opening 318.

In FIG. 10B, a gate insulating layer (not shown) is formed over anentire surface of the substrate 310 to cover the patterned first metallayer, the gate line 312, the common line 314, the gate electrode 316,and common electrode 320. Thereafter, the semiconductor line 325 and thedata line 328 are simultaneously formed on the gate insulating layerthrough a second mask process. The semiconductor line 325 and the dataline 328 have the same pattern shape because they are formed during thesame patterning process. The semiconductor line 325 may include amultiple layer of intrinsic amorphous silicon layer and impurity-dopedamorphous silicon layer, and the data line 328 may include a metallicmaterial. A source electrode 330 that overlaps the gate electrode 316and extends from the data line 328 and a drain electrode 332 that isspaced apart from the source electrode 330 are formed at the same timeas the semiconductor line 325 and the data 328. Further, a semiconductorlayer 326 extending from the semiconductor line 325 is also formed to bedisposed under the source and drain electrodes 330 and 332. A portion ofthe semiconductor layer 326 between the source and drain electrodes 330and 332 forms a channel by exposing the intrinsic amorphous siliconlayer.

The portion of the semiconductor layer 326 between the source and drainelectrodes 330 and 332 may be exposed through a process using adiffraction mask. Although not shown in the figures, after sequentiallyforming an intrinsic amorphous silicon layer, an impurity-dopedamorphous silicon layer and a metallic material layer on the gateinsulating layer, a photoresist (PR) layer, having a first thickness,may be formed on the metallic material layer. Afterwards, a diffractionmask having transmissive, diffractive and shielding regions is disposedover the PR layer. The PR layer may be irradiated through thediffraction mask. For example, when a negative type PR layer in which anexposed portion remains, the exposed semiconductor region corresponds tothe diffractive region of the diffraction mask and the source and drainelectrodes correspond to the transmissive region of the diffractionmask. After developing the exposed PR layer. A first PR pattern, havinga first thickness on the source and drain electrodes and a secondthickness on the exposed semiconductor region is obtained. Aftersequentially etching the intrinsic amorphous silicon layer, theimpurity-doped amorphous silicon layer and the metallic material, layerusing the first PR pattern as an etching mask, the first PR patternbecomes a second PR pattern such that portions having the initial secondthickness are removed through an ashing step. The semiconductor layer isetched using the second PR pattern as an etching mask. Thus, a portionof the semiconductor layer 316 may be exposed between the source anddrain electrodes 330 and 332 through an exposure process using adiffraction mask. The gate electrode 316, the semiconductor layer 316,the source electrode 330 and the drain electrode 332 form the thin filmtransistor (TFT) T.

In FIG. 10C, a passivation layer (not shown) is formed on the entiresurface of the substrate 310, and then patterned during a third maskprocess to form a drain contact hole 334 that exposes a portion of thedrain electrode 332.

FIG. 10D shows a fourth mask process through which the pixel electrode338 and the capacitor electrode 340 are formed. A transparent conductivelayer is first formed on the passivation layer having the drain contacthole 334, and then patterned by the fourth mask process. Thus, on thepassivation layer, formed are the pixel electrode 338, the capacitorelectrode 340 and the pixel connecting line 341. The pixel electrode 338includes first and second pixel electrode patterns 338 a and 338 b. Thefirst pixel electrode pattern 338 a is shaped like a ring and disposedbetween the first and second common electrode patterns 320 a and 320 b.The second pixel electrode pattern 338 b is shaped like a circle anddisposed inside the second common electrode pattern 320 b in the middleof the pixel region P. The capacitor electrode 340 includes the firstand second capacitor electrode patterns 340 a and 340 b which aredisposed over top and bottom portions of the first common electrodepattern 320 a, respectively. The pixel connecting line 341 is verticallydisposed in the pixel region P, crosses the common line 314, and isconnected to the first and second capacitor electrode patterns 340 a and340 b. The pixel connecting line 341 also connects the first and secondpixel electrode patterns 338 a and 338 b to each other. The pixelconnecting line 341 may be formed as a unitary pattern with the pixelelectrode 138 and the capacitor electrode 340 through one process. Thefirst capacitor electrode pattern 340 a contacts the drain electrode 332through the drain contact hole 334. Meanwhile, the transparentconductive layer for the pixel electrode 340 may be one of indium tinoxide (ITO), indium tin zinc oxide (ITZO) and indium zinc oxide (IZO).

FIG. 11 is a schematic plane view of an array substrate for an IPS-LCDdevice according to a fourth embodiment of the present invention. Thearray substrate of FIG. 11 is very similar to that of FIG. 7, but thearray substrate is complete throughout a four-mask process where adiffraction exposure is utilized to form the semiconductor layer and thesource and drain electrodes. Furthermore in this fourth embodiment, thearray substrate has an aperture area having a gyroidal shape by beingdefined by gyroidal common and pixel electrodes.

In FIG. 11, a gate line 412 is transversely arranged and a data line 428is disposed substantially perpendicular to the gate line 412. Crossingpoints of the gate and data lines 412 and 428 define a pixel region P onan array substrate. A thin film transistor (TFT) T is disposed in thepixel region P near a crossing of the gate and data line 412 and 428.The TFT T includes a gate electrode 416, a semiconductor layer 426, asource electrode 430 and a drain electrode 432. The gate electrode 416extends from the gate line 412, and the source electrode 430 extendsfrom the data line 428. The drain electrode 432 is spaced apart from thesource electrode 430 and overlaps a portion of the gate electrode 416.The data line 428 and the source and drain electrodes 420 and 432 areformed together with the semiconductor layer 426 during the samepatterning process such that a semiconductor line 425 is disposed underthe data line 428 having the same pattern shape as the data line 428.The semiconductor layer 426 extends from the semiconductor line 425 andis also disposed under the source and drain electrodes 430 and 432.

Within the pixel region P, a first common electrode pattern 420 a havinga rectangular shape is disposed. The first common electrode pattern 420a has a circular opening 418 in the middle thereof such that the firstcommon electrode pattern 420 a surrounds a boundary portion of the pixelregion P. A second common electrode pattern 420 b has a gyre shape andis disposed in the circular opening 418 by extending from the firstcommon electrode pattern 420 a. The first and second common electrodepatterns 420 a and 420 b form a common electrode 420. A common line 414crosses the data line 428 and connects the common electrode 420 to aneighboring common electrode (not shown) in a next pixel region. Thecommon line 414 may be formed as one united or integrated body with thecommon electrode 420.

A capacitor electrode 440 may be formed to overlap the first commonelectrode pattern 420 a and forms a storage capacitor with theoverlapped portions of the first common electrode pattern 420 a. One endof the capacitor electrode 440 is connected to a drain electrode 432 ofthe TFT T. A pixel electrode 438 having a gyre shape is also disposed inthe circular opening 418. The gyroidal pixel electrode 438 extendsbeginning from the capacitor electrode 440 alongside the gyroidal secondcommon electrode pattern 420 a. The first helical turn of the gyroidalpixel electrode 438 should be disposed between a first helical turn ofthe gyroidal second common electrode pattern 420 b and the first commonelectrode pattern 420 a in order to form a gyre-shaped aperture areabetween the common and pixel electrodes 420 and 438. Also, the pixelelectrode 438 is shaped and spaced apart from the second commonelectrode pattern 420 b. Similar to the second embodiment illustratedwith reference to FIG. 7, the capacitor electrode 440 may be formed tohave a smaller width than the first common electrode pattern 420 a andexpose a boundary portion of the first common electrode pattern 420 a togenerate a lateral electric field between the first common electrodepattern 420 a and the gyroidal pixel electrode 438.

FIGS. 12A to 12D are schematic plane views illustrating a four-maskprocess for fabricating the array substrate of FIG. 11.

In FIG. 12A, a first metal layer is formed on the substrate 410 and thenpatterned through a first mask process to form the gate line 412, thecommon line 414, and the common electrode 420 including first and secondcommon electrode patterns 420 a and 420 b. The gate electrode 416,extending the gate line 412 is also formed. The common line 414 connectsthe common electrode 420 to the neighboring common electrode (not shown)of the next pixel region. The first common electrode pattern 420 a isshaped like a rectangle and includes a circular opening 418 therein suchthat the first common electrode pattern 420 a overlaps peripheralportions of the pixel region P. The second common electrode pattern 420b has a gyre shape and extends from the first common electrode pattern420 a in the circular opening 418.

FIG. 12B shows a second mask process that is the same as the diffractionexposure method illustrated with reference to FIG. 10B.

In FIG. 12B, a gate insulating layer (not shown) is formed over anentire surface of the substrate 410 to cover the patterned first metallayer; the gate line 412, the common line 414, the gate electrode 416,and common electrode 420. Thereafter, the semiconductor line 425 and thedata line 428 are simultaneously formed on the gate insulating layerthrough a second mask process. Because the semiconductor line 425 anddata line 428 are manufactured during the same patterning process, thesemiconductor line 425 and the data line 428 have the same patternshape. The semiconductor line 425 may include a multiple layer ofintrinsic amorphous silicon layer and impurity-doped amorphous siliconlayer, and the data line 428 may include a metallic material. At thesame time of forming the semiconductor line 425 and the data line 428,formed are a source electrode 430 overlapping the gate electrode 416 andextending from the data line 428 and a drain electrode 432 spaced apartfrom the source electrode 430. Further, a semiconductor layer 426extending from the semiconductor line 425 may also be formed to bedisposed under the source and drain electrodes 430 and 432. A portion ofthe semiconductor layer 426 between the source and drain electrodes 430and 432 constitutes a channel “ch” by exposing the intrinsic amorphoussilicon layer, as illustrated with reference to FIG. 10B. Namely, thesemiconductor layer 426 may be exposed between the source and drainelectrodes 430 and 432 through an exposure process using a diffractionmask and the exposed semiconductor layer 426 may be referred to as achannel region “ch.” The gate electrode 416, the semiconductor layer426, the source electrode 430 and the drain electrode 432 constitute athin film transistor (TFT) T.

FIG. 12C shows a process of forming a drain contact hole 434. Apassivation layer (not shown) is formed over the entire of the substrate410 to cover the thin film transistor T. Then, the passivation layer(not shown) is patterned through a third mask process to form a draincontact hole 434 that exposes a portion of the drain electrode 432.

In FIG. 12D, a transparent conductive layer is formed on the passivationlayer having the drain contact hole 434, and then patterned through afourth mask process, thereby forming the capacitor electrode 440 and thegyre-shaped pixel electrode 438. The capacitor electrode 440 is disposedto overlap the first common electrode pattern 220 a and connected to thedrain electrode 432 through the drain contact hole 434. The pixelelectrode 438 having a gyre shape extends from the capacitor electrode440 alongside the gyroidal second common electrode pattern 420 b. Theextension of the pixel electrode 438 starts from a portion next to thebeginning of the gyre-shapes second common electrode pattern 420 b.Meanwhile, the capacitor electrode 440 should have a smaller width thanthe first common electrode pattern 420 a in order to prevent theelectrical interruption between the pixel electrode 438 and thecapacitor electrode 440.

In another embodiment, the IPS-LCD device may be fabricated using alift-off process. In a lift-off process, after forming a photoresist(PR) pattern on a first layer, a second layer is formed on the PRpattern and on the exposed first layer. The second layer is patterned byremoving a portion of the second layer on the PR pattern while strippingout the PR pattern. Accordingly, a second layer pattern is obtained tohave a desired shape.

FIGS. 13A to 13D are cross sectional views illustrating a lift-offprocess.

In FIG. 13A, first regions “VIa” and second regions “VIb” are defined ona substrate 450. PR patterns 452 having a step or height are formed onthe second region “VIb” of the substrate 450.

In FIG. 13B, a patterning material 454 is formed over the substrate 450to cover the PR patterns 452. The patterning material 454 is a metallicmaterial or a transparent conductive material. Although not shown inFIG. 13B, portions of the patterning material 454 on the PR patterns 452may be isolated from other portions on the substrate 450 because thestep or height of the PR patterns 452 affects the step coverage of thepatterning material 454 when forming the patterning material 454.

FIG. 13C shows a process of stripping off the PR patterns 454. Whenstripping the PR patterns 454 from the substrate 450, the portions 454 aof the patterning material 454 are also removed by the lift-off processwhile the other portions 454 b on the substrate 450 remain. Thus, asshown in FIG. 13D, the residual patterning material becomes desiredpatterns 456 on the substrate 450, especially corresponding to the firstregions “VIa” where the PR patterns did not exist.

The aforementioned lift-off process is much simpler that thephotolithograph process because it does not need exposure, developing,etching etc. The description will illustrate the array substrates formedby such lift-off process. If the lift-off process is utilized in formingthe aforementioned array substrate.

FIG. 14 is a plan view illustrating an array substrate for use in anIPS-LCD device according to a fifth embodiment of the present invention.The array substrate of FIG. 14 is similar to the first and thirdembodiments, but the array substrate of FIG. 14 is formed using athree-mask process in which a diffraction exposure and a lift-offprocess are utilized.

In FIG. 14, a gate line 512 is transversely arranged and a data line 528is disposed substantially perpendicular to the gate line 512. A pair ofgate and data lines 512 and 528 define one pixel region P on a substrate510. Common and pixel electrodes 520 and 538 having circular apertureareas, are formed within the pixel region P. Because the pixel electrode538 and the common electrode 520 have circular shapes, liquid crystaldetectors are the same in all directions and a color inversion along aspecific angle is prevented. A common line 514 runs from left to rightin the middle of the pixel region P. The common line is parallel to andspaced apart from the gate line 512.

At one ends of the gate and data lines 512 and 528, a gate pad 1310 anda data pad 1314 are respectively disposed. A gate pad terminal 1318 isdisposed over the gate pad 1310 and contacts the gate pad 1310 through afirst contact opening XVIa, whereas a data terminal 1320 is disposedover the data pad 1314 and the contacts the data pad 1314 through asecond contact opening XVIb.

A thin film transistor (TFT) T is disposed near a crossing of the gateand data lines 512 and 528. The TFT T includes a gate electrode 516, asemiconductor layer 526, a source electrode 530 and a drain electrode532. The gate electrode 516 extends from the gate line 512, and thesource electrode 530 extends from the data line 528. The drain electrode532 is spaced apart from the source electrode 530 and overlaps a portionof the gate electrode 516. The drain electrode 532 is elongatedtransversely and connected to a pixel connecting line 533 that is formedwith the drain electrode 532 as one united or integral body. A capacitorelectrode 535 is formed to overlap a previous gate line and form astorage capacitor CST with the overlapped portion of the previous gateline. The pixel connecting line 533 vertically crosses the middle of thepixel region P and connects the drain electrode 532 to the capacitorelectrode 535.

In the fifth embodiment, the data line 528, the source and drainelectrodes 520 and 532, the pixel connecting line 533 and the capacitorelectrode 535 are formed along with the semiconductor layer 526 duringthe same patterning process such that a semiconductor line 525 isdisposed under the data line 528. The semiconductor line has the samepattern shape as the data line 528. The semiconductor layer 526 may beelongated under both the pixel connecting line 533 and the capacitorelectrode 535. In particular, the semiconductor layer 526 may extendfrom the semiconductor line 525 under the source and drain electrodes530 and 532, the pixel connecting line 533 and the capacitor electrode535.

Similar to the first and third embodiments explained with reference toFIGS. 5 and 9, the common electrode 520 includes a first commonelectrode pattern 520 a that surrounds the pixel region P and has acircular opening 518 in the middle, and a second common electrodepattern 520 b within the circular opening 518. First half portions ofthe first and second common electrode patterns 520 a and 520 b extendfrom the common line 514 in an upward direction, and second halfportions of the first and second common electrode patterns extend in adownward direction. Thus, the first and second common electrode patterns520 a and 520 b are connected to the common line 514. The first commonelectrode pattern 520 a is shaped like a rectangle and has a circularopening 518, while the second common electrode pattern 520 b is shapedlike a ring. Because the common line 514 transversely crosses the pixelregion P, the common line 514 corresponds to and crosses along adiametric line of the circular band shaped second common electrodepattern 520 b and the circular opening 518.

The pixel electrode 538 includes first and second pixel electrodepatterns 538 a and 538 b. The first pixel electrode pattern 538 a has asemicircular arc and is disposed between the first and second commonelectrode patterns 520 a and 520 b, and the second pixel electrodepattern 538 b has a rod shape and is disposed inside the circular bandshaped second common electrode pattern 520 b. In this fifth embodimentof the present invention, the first and second pixel electrode patterns520 a and 520 b are formed to directly contact the pixel connecting line533. The circular band shaped first pixel electrode pattern 538 acrosses and directly contacts the pixel connecting line 533. The secondpixel electrode pattern 538 b is located in the center of the pixelregion P where the common and pixel connecting lines 514 and 533 crosseach other. Especially, the second pixel electrode pattern 538 b isdisposed within an area of the pixel connecting line 533. Accordingly,the pixel electrode 538, having the first and second electrode patterns538 a and 538 b, receives data signals from the thin film transistor T.

In the fifth embodiment the pixel region P is divided into multidomains,e.g., four domains, by the pixel connecting line 533 and the common line514. Moreover, the aperture areas defined between the common and pixelelectrodes 520 and 538 have circular shapes similar to the first andthird embodiments of FIGS. 5 and 9, to prevent color shift and improvethe image quality and viewing angle of the IPS-LCD device.

FIGS. 15A-15D are schematic plan views illustrating a three mask processof fabricating an array substrate for an IPS-LCD device according to afifth embodiment of the present invention.

In FIGS. 15A, 25A and 26A, a gate line 512 and a common line 514 areformed on a substrate 510 during a first mask process. At the same time,a gate electrode 516 connected to the gate line 512, a common electrode520 connected to the common line 514, and a gate pad 1310 connected toone end of the gate line 512 may be formed. Similar to the first andthird embodiments described with reference to FIGS. 6A and 10A,respectively, the gate line 512 and the common line 514 are transverselydisposed. The gate electrode 516 extends from the gate line 512. Thecommon electrode 520 includes first and second common electrode patterns520 a and 520 b. The first common electrode pattern 520 a includes acircular opening 518. First half portions of the first and second commonelectrode patterns 520 a and 520 b extend from the common line 514 in anupward direction, and second half portions extend in a downwarddirection. The first common electrode pattern 520 a is shaped like arectangle within the pixel region P and includes a circular opening 518such that the first common electrode pattern surrounds a boundaryportion of the pixel region P. The second common electrode pattern 520 bhas a ring shape and is disposed within the circular opening 518. Thecommon line 514 horizontally crosses the middle of the pixel region Psuch that it runs along the diametric line of the circular band shapedsecond common electrode pattern 520 b and the circular opening 518.

In FIGS. 15B, 25B and 26B, after forming a gate insulating layer 1312 onthe gate line 512 and the common line 514, a semiconductor layer 526 anda data line 528 are simultaneously formed on the gate insulating layer1312 through a second mask process. The semiconductor layer 526 mayinclude a multiple layer of intrinsic amorphous silicon layer andimpurity-doped amorphous silicon layer and the data line 528 may includea metallic material. At the same time, a source electrode 530 is formedto overlap the gate electrode 516 and extend from the data line 528 anda drain electrode 532 spaced apart from the source electrode 530.Because the semiconductor layer 526 is formed with the source and drainelectrodes 530 and 532 during the same patterning process and using adiffraction mask similar to the third embodiment illustrated withreference to FIG. 10B, a semiconductor line 525 is formed under the dataline. The semiconductor line 525 has the same pattern shape as the dataline 528. Furthermore, when forming the data line 528 and the source anddrain electrodes 530 and 532, a pixel connecting line 533 and acapacitor electrode 535 are also formed as a single unitary pattern withthe drain electrode 532. The capacitor electrode 535 is formed over theprevious gate line to form the storage capacitor, and the pixelconnecting line 533 is disposed vertically crossing the pixel region Pand connects the drain electrode 532 to the capacitor electrode 535. Thesemiconductor layer 536, extending from the semiconductor line 535, maybe formed to be disposed under the pixel connecting line 533 and thecapacitor electrode 535. Moreover, a portion of the semiconductor layer536 between the source and drain electrodes 530 and 532 is removedthrough an exposure process using the diffraction mask, and forms achannel “ch” by exposing the intrinsic amorphous silicon layer. The gateelectrode 516, the semiconductor layer 526, the source electrode 530 andthe drain electrode 632 form a thin film transistor (TFT) T.

FIGS. 15C, 25C and 26C illustrate a step of forming a photoresist (PR)pattern 536 and a transparent conductive layer 537. After forming theTFT T, a passivation layer 1316 is formed over an entire of thesubstrate 510. Then, the photoresist material is first formed over anentire surface of the substrate and then patterned during a third maskprocess, to form the PR pattern 536. The PR pattern 536 includeselectrode areas “II” where a PR material is removed. The electrode area“II” includes first and second electrode area “IIa” and “IIb.” The firstelectrode area “IIa” has a semicircular arc and is disposed between thefirst and second common electrode patterns 520 a and 520 b. The secondelectrode area “IIb” has a rod shape in a center portion of the pixelregion P wherein the pixel connecting line 533 perpendicularly crossesthe common line 514. After forming the PR pattern 536, portions of thepassivation and gate insulating layers 1312 and 1316, which are areasexposed by the electrode area “II”, are removed using the PR pattern 536as a mask. At this time of etching, the first contact opening XVIa andthe second contact opening XVIb are also formed. As mentioned before,the first contact opening XVIa exposes the gate pad 1310, and the secondcontact opening XVIb exposes the data pad 1314. After the etchingprocess, the transparent conductive layer 537 is formed on an entiresurface of the substrate 510 to cover the PR pattern 536.

In FIG. 15D, 25D and 26D, a pixel electrode 538 is obtained by strippingthe PR pattern 536 (of FIG. 15C). At this time of the stripping process,a gate pad terminal 1318 and a data pad terminal 1320 are also obtained.When the PR pattern 536 (of FIG. 15C) is stripped out, a portion of thetransparent conductive layer 537 (of FIG. 15C) on the PR pattern 535 (ofFIG. 15C) is also removed. Accordingly, only the transparent conductiveportion not on the PR pattern 536 (of FIG. 15C) remains and the residualtransparent conductive patterns become the pixel electrode 538, the gatepad terminal 1318 and the data pad terminal 1320. In this step of thelift-off process shown in FIG. 15D, 25D and 26D, an additionalphotolithographic process including exposure and development is notnecessary such that the array substrate can be fabricated using thethree-mask process.

Similar to the first and third embodiment, the pixel electrode 538includes first and second pixel electrode patterns 538 a and 538 b. Thefirst pixel electrode pattern 538 a has a semicircular arc and isdisposed between the first and second common electrode patterns 520 aand 520 b. The second pixel electrode pattern 538 b has a rod shape andis disposed in a center portion of the pixel connecting line 533. Thefirst and second pixel electrode patterns 538 a and 538 b directlycontacts the pixel connecting line 533 because there the passivationlayer is remover and there is no insulator between the pixel connectingline 533 and the pixel electrode 538.

FIG. 16 is a plan view of an array substrate for use in an IPS-LCDdevice according to a sixth embodiment of the present invention. Thearray substrate of FIG. 16 is similar to that of FIG. 14, but the commonand pixel electrodes 620 and 638 are formed together during the sameprocess step. Also in the sixth embodiment of the present invention, thefabrication process utilizes the aforementioned diffraction exposure andlift-off process such that the array substrate of FIG. 16 can becompleted using a three-mask process.

In FIG. 16, a gate line 612 is transversely arranged and a data line 628is disposed substantially perpendicular to the gate line 612. The gateand data lines 612 and 628 define a pixel region P on an array substrateby crossing each other. A thin film transistor (TFT) T is disposed inthe pixel region P near a crossing of the gate and data line 612 and628. The TFT T includes a gate electrode 616, a semiconductor layer 626,a source electrode 630 and a drain electrode 632. The gate electrode 616extends from the gate line 612, and the source electrode 630 extendsfrom the data line 628 and overlaps one end portion of the gateelectrode 616. The drain electrode 632 is spaced apart from the sourceelectrode 630 and overlaps the other end portion of the gate electrode616. In this process step, the semiconductor material and the metallayer are patterned during the same time using the diffraction mask suchthat the data line 628 and the source and drain electrodes 620 and 632are formed along with the semiconductor layer 626. A semiconductor line625 is formed under the data line 628 and has the same pattern shape asthe data line 628. The semiconductor layer 626 extends from thesemiconductor line 625 and is also disposed under the source and drainelectrodes 630 and 632. Furthermore, a pixel connecting line 633 and acapacitor electrode 635 are also formed at the time of forming thesource and drain electrodes 630 and 632. The capacitor electrode 635 isdisposed overlapping a portion of the previous gate line 612 and formsthe storage capacitor with the overlapped portion of the previous gateline 612. The pixel connecting line 633 vertically crosses the pixelregion P and is substantially perpendicular to the common line 614. Thepixel connecting line 633 connects the drain electrode 632 to thecapacitor electrode 635. The drain electrode 632, the pixel connectingline 633 and the capacitor electrode 635 may be formed as a singleunitary pattern. Although not shown in FIG. 16, the semiconductor layer626 extending from the semiconductor line 625 may be elongated under thepixel connecting line 633 and the capacitor electrode 635.

Within the pixel region P, a first common electrode pattern 620 a havinga rectangular shape is disposed. The first common electrode pattern 620a has a circular opening in the middle and is divided into two partsincluding left and right parts. The first common electrode pattern 620 adoes not overlap the pixel connecting line 633, such that the pixelconnecting line 633 divides the first common electrode pattern 620 ainto left and right parts. The second common electrode pattern 620 b isdisposed inside the circular opening of the first common electrodepattern 620 b, and are divided into two parts including left and rightsemicircular arcs. Like the first common electrode pattern 620 a, thesecond common electrode pattern 620 b does not overlap the pixelconnecting line 633 such that the left and right semiconductor arcs ofthe second common electrode pattern 620 b are divided by the pixelconnecting line 633. The first and second common electrode patterns 620a and 620 b overlap a portion of the common line 614 and directlycontact the common line 614.

Within the pixel region P, a pixel electrode 638 is also formed. Thefirst pixel electrode 638 includes a first pixel electrode pattern 638 aand a second pixel electrode pattern 638 b. The first pixel electrodepattern 638 a is disposed between the first and second common electrodepatterns 620 a and 620 b and is divided into two part including upperand lower semicircular arcs. The upper and lower semicircular arcs ofthe first pixel electrode pattern 638 a cross over the pixel connectingline 633, but do not overlap the common line 614. Thus, the first pixelelectrode pattern 638 a is divided by the common line 614 into the upperand lower semicircular arcs. The second pixel electrode pattern 638 b isshaped like a rod and disposed over the pixel connecting line 633 in themiddle of the pixel region P. The second pixel electrode pattern 638 bshould not be out of the area of pixel connecting line 633 because thesecond pixel electrode pattern 638 b contacts the common line 614 withreceiving the common voltage and does not generate the electric field ifthe second pixel electrode pattern 638 b overlaps the common electrode614. The second pixel electrode pattern 638 b is formed on the pixelconnecting line 633 and directly contacts the pixel connecting line 633.

FIGS. 17A to 17D are schematic plane views illustrating a three-maskprocess for fabricating the array substrate of FIG. 16. As discussedabove, the fabrication process utilizes both the diffraction mask andthe lift-off process to accomplish the three-mask process.

In FIG. 17A, a gate line 612 and a common line 614 are formed on asubstrate 610 during a first mask process. At the same time, a gateelectrode 616, connected to the gate line 612, may be formed.

In FIG. 17B, after forming a gate insulating layer (not shown) on thegate line 612 and the common line 614, a semiconductor line 625, asemiconductor layer 626 and a data line 628 are simultaneously formed onthe gate insulating layer through a second mask process. Thesemiconductor layer 626 includes a multiple layer of intrinsic amorphoussilicon layer and impurity-doped amorphous silicon layer, and so doesthe semiconductor line 625. The data line 628 may include a metallicmaterial. At the same time of forming the data line 628, a sourceelectrode 630 is formed to overlap the gate electrode 616 and extendfrom the data line 628. A drain electrode 632 is spaced apart from thesource electrode 630. Because the semiconductor layer 626 is formed withthe source and drain electrodes 630 and 632 during the same patterningprocess and using a diffraction mask similar to the third and fiveembodiments illustrated with reference to FIGS. 10B and 15B, thesemiconductor line 625 under the data line has the same pattern shapewith the data line 628. Furthermore, when forming the data line 628 andthe source and drain electrodes 630 and 632, a pixel connecting line 633and a capacitor electrode 635 are also formed as a single unitary orintegrated pattern with the drain electrode 632. The capacitor electrode535 is formed over the previous gate line to form the storage capacitor,and the pixel connecting line 533 is disposed vertically to cross thepixel region P and connects the drain electrode 632 to the capacitorelectrode 635. Although not shown in FIG. 17B, the semiconductor layer636 extends from the semiconductor line 635 and may be disposedunderneath the pixel connecting line 633 and the capacitor electrode635. Moreover, a portion of the semiconductor layer 636 between thesource and drain electrodes 630 and 632 may be removed through anexposure process using the diffraction mask to form a channel “ch” byexposing the intrinsic amorphous silicon layer. The gate electrode 616,the semiconductor layer 626, the source electrode 630 and the drainelectrode 632 form a thin film transistor (TFT) T.

In FIG. 17C, a photoresist (PR) layer is applied over an entire surfaceof the substrate 610, and then patterned using a third mask process toform a photoresist (PR) pattern 635. The PR pattern 636 includeselectrode areas EA where a PR material is removed during the patterningprocess. The electrode areas EA include first to seventh electrode areasEA1-EA7. The first and second electrode areas, EA1 and EA2, havesemicircular-rounded sides, respectively, which face to each other. Thefirst and second electrode areas EA1 and EA2 are shaped like a rectangleand surrounds a boundary portion of the pixel region P. Each of thethird and fourth electrode areas EA3 and EA4 is shaped like asemicircular arc. The third and fourth electrode areas EA3 and EA4 faceeach other and are surrounded by the first and second electrode areasEA1 and EA2. The third and fourth electrode areas EA3 and EA4 cross thepixel connecting line 633, but do not cross the common line 614. Thefifth and sixth electrode areas EA5 and EA6 are also shaped likesemicircular arcs and face each other. The fifth and sixth electrodeappears EA5 and EA6 are surrounded by the third and fourth electrodeareas EA3 and EA4. The fifth and sixth electrode areas EA5 and EA6 crossthe common line 614, respectively, but do not cross the pixel connectingline 633. The seventh electrode area EA7 is shaped like a rod, disposedwithin the area of the pixel connecting line 633 and is surrounded bythe fifth and sixth electrode areas EA5 and EA6. The seventh electrodearea EA7 exposes only a portion of the pixel connecting line 633.

After forming the PR pattern 635, the underlying gate insulating layer(not shown) is etched using the PR pattern 635 as an etching mask.Accordingly, the gate insulating layer under the first to sixthelectrode areas EA1 to EA6 is removed. Because the pixel connecting line633 covers the gate insulating layer in the seventh electrode area EA7,the gate insulating layer in the seventh electrode area EA7 is notremoved and the common line 614 in the seventh electrode area EA7 is notexposed. After etching the gate insulating layer, a transparentconductive layer 637 is formed on an entire surface of the substrate 610to cover the PR pattern 635.

In FIG. 17D, a pixel electrode 638 and a common electrode 620 areobtained by stripping the PR pattern 636 (of FIG. 17C), e.g., thelift-off process. When the PR pattern 636 (of FIG. 17C) is stripped out,portions of the transparent conductive layer 637 (of FIG. 17C) on the PRpattern 636 (of FIG. 17C) are also removed. Accordingly, only thetransparent conductive portions not on the PR pattern 636 remains andthe residual transparent conductive patterns become the pixel electrode638 and the common electrode 620. In this step of the lift-off processshown in FIG. 17D, an additional photolithographic process includingexposure and development is not necessary.

As described with reference to FIG. 16, the pixel electrode 638 includesfirst and second pixel electrode patterns 638 a and 638 b and the commonelectrode 620 includes first and second common electrode patterns 620 aand 620 b. The first common electrode pattern 638 a corresponds to thefirst and second electrode areas EA1 and EA2 (of FIG. 17C), and thesecond common electrode pattern 638 b corresponds to the fifth and sixthelectrode areas EA5 and EA6 (of FIG. 17C). The first pixel electrodepattern 638 a corresponds to the third and fourth electrode areas EA3and EA4 (of FIG. 17C), and the second pixel electrode pattern 638 bcorresponds to the seventh electrode area EA7. Because the gateinsulating layer is removed within the first, second, fifth and sixthelectrode areas (of FIG. 17C) the first and second common electrodepatterns 620 a and 620 b directly contact the common line 614. Moreover,the first and second pixel electrode patterns 638 a and 638 b maydirectly contact the pixel connecting line 633 because there is noinsulator on the pixel connecting line 633.

In the fifth embodiment, the pixel electrode 538 and the commonelectrode 520 are formed of the same material during the same process,and directly contact the pixel connecting line 633 and the common line614, respectively. Accordingly, if the common electrode 620 crosses thepixel connecting line 633, the common electrode 620 may directly contactthe pixel connecting line 633 and may cause an undesirable electricalshort. Similarly, if the pixel electrode 638 crosses the common line614, the pixel electrode 638 may directly contact the common line 614.Accordingly, the common electrode 620 and the pixel electrode 638 aredisposed to not overlap the pixel connecting line 633 and the commonline 614, respectively.

The first common electrode pattern 620 a has a rectangular outline andmay be divided into two parts that face each other. The opposite sidesof the two parts of the first common electrode pattern 620 a haverounded shapes. The second common electrode pattern 620 b also have theseparate two parts (i.e., left and right parts) each being shaped like asemicircular arc. The first pixel electrode pattern 638 a also has twoseparated portions each having a semicircular arc and disposed betweenthe first and second common electrode patterns 620 a and 620 b. Inparticular, the second pixel electrode pattern 638 b is disposed onlyinside the area of pixel connecting line 633.

FIG. 18 show simulation testing results of gray level and liquid crystaldirector conducting on the IPS-LCD device of the present inventiondepending on the applied voltages. The simulation testing is initiallyperformed in a normally black mode where the IPS-LCD device generatesblack color when the voltage is not applied. As shown in FIG. 18, whenthe voltage increases, the brightness also increases and the liquidcrystal directors are uniform in all directions. Specifically, whereverthe observer looks at the IPS-LCD device, the liquid crystal directorwill be the same regardless of the directions.

FIG. 19 is a schematic plan view of an array substrate for an IPS-LCDdevice according to a seventh embodiment of the present invention. Inthe seventh embodiment of the present invention, the IPS-LCD deviceincludes red, green, blue and white sub-pixel regions each having asquare shape. The four sub-pixels form one pixel.

In FIG. 19, red, green, blue and white sub-pixel regions “PR,” “PG,”“PB,” and “PW” form one pixel region “PP” of a square shape. A commonelectrode 720 including first and second common electrode patterns 720 aand 720 b is formed in each sub-pixel region “PR,” “PG,” “PB,” and “PW.”The first common electrode pattern 720 a including a circular opening718 surrounds a boundary portion of each sub-pixel region “PR,” “PG,”“PB,” or “PW.” The second common electrode pattern 720 b has a ringshape in the center of the circular opening 718. Also, a pixel electrode738 having a circular band shaped first pixel electrode pattern 738 aand a circular second pixel electrode pattern 738 b are disposed withinthe circular opening 718. The common and pixel electrodes 720 and 738form circular aperture areas. Because each sub-pixel region “PR,” “PG,”“PB,” or “PW” has a square shape and the white sub-pixel “PW” isemployed, aperture ratio is dramatically improved rather than when onlyred, green and blue sub-pixels are employed. Although FIG. 19 shows thearray substrate having the circular aperture areas, the array substratehaving the gyre aperture area can have such four sub-pixel structure.

FIG. 20 is a schematic plan view illustrating one pixel of an arraysubstrate for use in an IPS-LCD device according an eighth embodiment ofthe present invention. The array substrate of FIG. 20 has a very similarelemental structure to FIG. 5, but includes an enlarged storagecapacitor.

As shown in FIG. 20, a gate line 812 is transversely arranged and a dataline 828 is disposed substantially perpendicular to the gate line 812.The gate and data lines 812 and 828 define a pixel region “P” on anarray substrate. A thin film transistor (TFT) T is connected to the gateline 812 and the data line 828.

A common electrode 820 including first and second common electrodepatterns 820 a and 820 b is formed in the pixel region P. The firstcommon electrode pattern 820 a, including a circular opening 818,surrounds a boundary portion of the pixel region P, and the secondcommon electrode pattern 820 b has a ring shape inside the circularopening 818.

A pixel electrode 838 includes first and second pixel electrode patterns838 a and 838 b. The first pixel electrode pattern 838 a has a ringshape and is disposed between the first and second common electrodepatterns 820 a and 820 b. The second pixel electrode pattern 838 b has acircular shape and is disposed inside the circular band shaped secondcommon electrode pattern 820 b.

A capacitor electrode 840 includes first and second capacitor electrodepatterns 840 a and 840 b. The first capacitor electrode pattern 840 aoverlaps a bottom portion of the first common electrode pattern 820 aand is connected to the thin film transistor T. The second capacitorelectrode pattern 840 b overlaps a top portion of the first commonelectrode pattern 820 a and the previous gate line 812 of a neighboringpixel region. The first and second capacitor electrode patterns 840 aand 840 b and the overlapped top and bottom portions of the first commonelectrode pattern 820 a form a first storage capacitor CST1. And, thesecond capacitor electrode pattern 840 b and the overlapped portion ofthe previous gate line 812 form a second storage capacitor CST2. Becausethe second storage capacitor CST is enlarged over the previous gate lineand the first and second storage capacitors CST1 and CST2 are connectedsubstantially in parallel to each other, a total storage capacitor CSTis raised without reduction of aperture ratio.

FIG. 21 is a schematic plan view of an array substrate for an IPS-LCDdevice according to a ninth embodiment of the present invention. Thearray substrate of FIG. 21 is similar to FIG. 7, but includes anenlarged storage capacitor.

In FIG. 21, the array substrate includes a gyroidal pixel electrode 938and a gyroidal second common electrode pattern 920 b such that the arraysubstrate has an aperture area similar to the gyre shape of the secondembodiment illustrated in FIG. 7. A capacitor electrode 940 overlappinga first common electrode pattern 920 a is enlarged over a previous gateline 912 of a previous pixel region. Thus, the capacitor electrode 940forms a first storage capacitor CST1 with the overlapped portion of thefirst common electrode pattern 920 a, and forms a second storagecapacitor CST2 with the overlapped portion of the pervious gateelectrode 912. Therefore, a total storage capacitor CST has improvedcapacitance without reduction of aperture ratio and the IPS-LCD devicecan be driven in stable.

FIG. 22 is a schematic plan view illustrating one pixel of a colorfilter substrate that is attached to the aforementioned array substrate.The color filter substrate of FIG. 22 can be utilized for the arraysubstrate having one of the circular aperture areas and the gyreaperture areas.

A black matrix 1054 having a rectangular-like opening 1052 is formed ona substrate 1050. A color filter 1056 is formed on the substrate 1050 tobe fit into the rectangular-like opening 1052, such that the blackmatrix 1054 becomes a border of neighboring color filters formed nextpixels. In FIG. 22, a first area “Xa” denotes an area where the circularor gyroidal electrodes are formed. A second area “Xb” denotes an areathat corresponds in position to the rectangular electrode formed inarray substrate. If the first area “Xa” for the circular or gyroidalelectrodes overlaps the black matrix 1054, it forms a first overlappedarea “Xc.” And if the second area “Xb” for the rectangular electrodeoverlaps the black matrix 1054, it forms a second overlapped area “Xd.”Generally, it is noticeable that the second overlapped area “Xd” islarger than the first overlapped area “Xc.” Namely, when the colorfilter substrate is misaligned with the array substrate when they areattached to each other, the deduction of aperture ratio is minimizedbecause the circular or gyroidal electrode overlaps less of the blackmatrix 1054 than the rectangular electrode (i.e., Xc<Xd).

FIG. 23 is a plan view illustrating one pixel of an array substrate foruse in an IPS-LCD device according to a tenth embodiment of the presentinvention.

As shown in FIG. 23, a gate line 1112 is transversely arranged and adata line 1128 is disposed substantially perpendicular to the gate line1112. The gate and data lines 1112 and 1128 define a pixel region “P” onan array substrate. A thin film transistor (TFT) T is disposed near thegate and data lines 1112 and 1128 and is connected to the gate line 1112and the data line 1128.

A common electrode 1120 including first and second common electrodepatterns 1120 a and 1120 b is formed in the pixel region P. The firstcommon electrode pattern 1120 a is shaped like a rectangle and includesa rectangular-like opening 1118. The first common electrode pattern 1120a surrounds a boundary portion of the pixel region P. The second commonelectrode pattern 1120 b has a ring shape in the rectangular-likeopening 1118. The common electrode 1120 is connected to a common line1114 that is substantially parallel with and spaced apart from the gateline 1112. The common line 1114 runs from left to right in the middle ofthe pixel region P.

A capacitor electrode 1140 including first and second capacitorelectrode patterns 1140 a and 1140 b. The first capacitor electrodepattern 1140 a is disposed over a bottom portion of the first commonelectrode pattern 1120 a and is connected to the TFT T. The secondcapacitor electrode pattern 1140 b is disposed over a top portion of thefirst common electrode pattern 1120 a. In particular, the capacitorelectrode 1140 is formed in an area where the first common electrodepattern 1120 a is disposed such that the capacitor electrode 1140overlaps the first common electrode pattern 1120 a and forms a storagecapacitor with the overlapped portions of the first common electrodepattern 120 a. The first capacitor electrode pattern 1140 a and thesecond capacitor electrode pattern 1140 b are disposed in bottom and topportions of the pixel region P, respectively.

A pixel electrode 1138 including first and second pixel electrodepatterns 1138 a and 1138 b is connected to the capacitor electrode 1140through a pixel connecting line 1141. The first pixel electrode pattern1138 a has a ring shape and is disposed between the first and secondcommon electrode patterns 1120 a and 1120 b, and the second pixelelectrode pattern 238 b has a circular shape and is disposed inside thecircular band shaped second common electrode pattern 1120 b,specifically at a crossing of the common and pixel connecting lines 1114and 1141.

In the tenth embodiment, the first and second capacitor electrodepatterns 1140 a and 1140 b face to and are spaced apart from each other.The first and second capacitor electrode patterns 1140 a and 1140 b havea substantially rectangular shape and are parallel to each other. Thefirst and second capacitor electrode patterns 1140 a and 1140 b areconnected to the first and second pixel electrode patterns 1138 a and1138 b through the pixel connecting line 1141.

In FIG. 23, aperture areas are formed in between the first pixelelectrode pattern 1138 a and the second common electrode pattern 1120 band between the second pixel electrode pattern 1138 b and the commonelectrode pattern 1120 b. In the tenth embodiment, the first commonelectrode pattern 1120 a is shaped like a rectangular ring shape, andthus the rectangular-like opening 1118 has four corner opening portions“XI.” Therefore, the aperture area of the pixel region P is enlarged asmuch as the four corner opening portions “XI.” Namely, the apertureratio of the array substrate increases and the brightness of the IPS-LCDalso increases.

Although not shown in FIG. 23, the first common electrode pattern 1120 aand the capacitor electrode 1140 may be utilized in an array substratehaving the gyre common and pixel electrodes to produce the gyroidalaperture area.

FIG. 24 is a schematic plan view of an array substrate for an IPS-LCDdevice according to an eleventh embodiment of the present invention.

As shown in FIG. 24, gate lines 1212 are transversely arranged and datalines 1228 are disposed substantially perpendicular to the gate lines1212. Pairs of the gate and data lines 1212 and 1228 define a pixelregion P on an array substrate. A semiconductor line 1225 is formed tohave the same pattern shape as the data line 1228. A thin filmtransistor (TFT) T is disposed at one corner of the pixel region P andis connected to the gate line 1212 and the data line 1228. Thesemiconductor line 1225 extends to the TFT T and then forms asemiconductor layer 1226 under the source and drain electrodes 1230 and1232. A pixel connecting line 1241 vertically crosses the middle of thepixel region P, and is connected to the drain electrode 1232 of the TFTT.

A common electrode 1220 including first and second common electrodepatterns 1220 a and 1220 b is formed in the pixel region P. The firstcommon electrode pattern 1220 a is shaped like a rectangle and includesa circular opening 1218 such that the first common electrode pattern1220 a surrounds a boundary portion of the pixel region P. The secondcommon electrode pattern 1220 b has a ring shape and is disposed insidethe circular opening 1218.

A pixel electrode 1238 includes first and second pixel electrodepatterns 1238 a and 1238 b. The first pixel electrode pattern 1238 a hasa ring shape and is disposed between the first and second commonelectrode patterns 1220 a and 1220 b, and the second pixel electrodepattern 1238 b has a circular shape and is disposed inside the circularband shaped second common electrode pattern 1220 b. The pixel electrode1238 and the common electrode 1220 form circular band shaped apertureareas and may be formed of the same material during the same process.For example, the pixel electrode 1238 and the common electrode 1220 maybe formed of a transparent conductive material using a lift-off process.

A passivation layer (not shown) having a low dielectric constant isinterposed between the data line 1228 and the common electrode 1220 andbetween the pixel connecting line 1241 and the pixel electrode 1238. Forexample, benzocyclobutene (BCB) or acrylic resin may be used for thepassivation layer. The passivation layer has first and second contactholes 1244 and 1246 that expose the common line 1214 and the pixelconnecting line 1241, respectively. The first contact holes 1244 aredisposed under the common electrode 1220 and expose portions of thecommon line 1214 such that first contact holes 1244 contact the commonelectrode 1220 to the common line 1214. The second contact holes 1246are disposed under the pixel electrode 1238 and expose portions of thepixel connecting line 1241 such that they connect the pixel electrode1238 to the pixel connecting line 1241. Specifically, the commonelectrode 1220 is connected to the common line 1214 through the firstcontact holes 1244 of the passivation layer, and the pixel electrode1238 is connected to the pixel connecting line 1241 through the secondcontact holes 1246 of the passivation layer.

In the eleventh embodiment of FIG. 24, because the passivation layerhaving a low dielectric constant is interposed between the data line1228 and the common electrode 1220 and between the pixel connecting line1241 and the pixel electrode 1238, electric interferences between themmay be reduced. Accordingly, the common electrode 1220 can be enlargedin an area and the aperture ratio is further improved. Moreover, becausethe array substrate shown in FIG. 24 includes the passivation layerhaving contact holes for high aperture ratio, the array substrate may beformed using a four mask process in which the common and pixelelectrodes are formed of the same material during the same process.

In the present invention, because the common electrode and the pixelelectrode have a circular shape, directors of liquid crystal moleculesare the same in all directions. Thus, contrast ratio and viewing angleare improved without color inversion in a specific angle.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the array substrate of thepresent invention without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

1. An array substrate for use in an in-plane switching liquid crystaldisplay device, comprising: a gate line on a substrate; a data linecrossing the gate line to define a pixel region having an aperture area;a thin film transistor disposed at one corner of the pixel region andconnected to the gate line and the data line, the thin film transistorincluding a semiconductor layer; a common electrode disposed in thepixel region and having first and second common electrode patterns,wherein the first common electrode pattern is substantiallyrectangle-shaped and has a substantially circular opening in the middlethereof, and the second common electrode pattern is disposed in thesubstantially circular opening and has a substantially gyre shape; acommon line substantially perpendicular to and crossing the data lineand connecting the common electrode to a neighboring common electrode ina neighboring pixel region; a capacitor electrode overlapping the firstcommon electrode pattern, the capacitor electrode connected to the thinfilm transistor; and a pixel electrode disposed within the substantiallycircular opening and having a substantially gyre shape along a side ofthe second common electrode pattern, wherein the pixel electrode and thesecond common electrode pattern each have the substantially gyre shape,wherein the aperture area is substantially gyre shaped.
 2. The arraysubstrate of claim 1, wherein the second common electrode patternextends from the first common electrode pattern.
 3. The array substrateof claim 2, wherein the pixel electrode extends from the capacitorelectrode, the extension of the pixel electrode starting next to theextension of the second common electrode pattern.
 4. The array substrateof claim 1, wherein a first helical turn of the pixel electrode islocated between the first common electrode pattern and a first helicalturn of the second common electrode pattern.
 5. The array substrate ofclaim 1, wherein the common line is formed as one unitary pattern withthe common electrode.
 6. The array substrate of claim 1, wherein thecapacitor electrode has a substantially rounded side along thesubstantially circular opening of the first common electrode pattern. 7.The array substrate of claim 1, wherein four neighboring pixel regionscorrespond to red, green, blue and white colors, respectively.
 8. Thearray substrate of claim 1, wherein the capacitor electrode and thecommon electrode overlap to form a first storage capacitor.
 9. The arraysubstrate of claim 8, wherein the capacitor electrode overlaps aprevious gate line of a previously neighboring pixel region to form asecond storage capacitor.
 10. The array substrate of claim 1, furthercomprising a semiconductor line under the data line and having the samepattern shape as the data line, wherein the semiconductor layer extendsfrom the semiconductor line.
 11. A method of forming an array substratefor an in-plane switching liquid crystal display device, comprising:forming a gate line having a gate electrode, a common electrode havingfirst and second common electrode patterns, and a common linesubstantially parallel to and spaced apart from the gate line on asubstrate using a first mask process, wherein the first common electrodepattern is substantially rectangle-shaped and has a substantiallycircular opening in the middle thereof, and the second common electrodepattern is disposed in the substantially circular opening and has asubstantially gyre shape; forming a gate insulating layer on the gateline, the common electrode and the common line; forming a semiconductorlayer on the gate insulating layer and over the gate electrode using asecond mask process; forming a data line that crosses the gate line todefine a pixel region having an aperture area, a source electrodeextending from the data line, and a drain electrode spaced apart fromthe source electrode using a third mask process, wherein the source anddrain electrodes overlap opposite end portions of the semiconductorlayer, the semiconductor layer being exposed between the source anddrain electrodes, and the gate electrode, the semiconductor layer, thesource electrode and the drain electrode forming a thin film transistor;forming a passivation layer over an entire surface of the substrate tocover the thin film transistor and patterning the passivation layerusing a fourth mask process to form a drain contact hole to expose aportion of the drain electrode; and forming a capacitor electrodeoverlapping the first common electrode pattern, and a pixel electrodewithin the substantially circular opening and having a substantiallygyre shape along a side of the second common electrode pattern using afifth mask process, wherein the capacitor electrode is connected to thethin film transistor, and the pixel electrode and the second commonelectrode pattern each have the substantially gyre shape, wherein theaperture area is substantially gyre shaped.
 12. The method of claim 11,wherein the second common electrode pattern extends from the firstcommon electrode pattern.
 13. The method of claim 12, wherein the pixelelectrode extends from the capacitor electrode, the extension of thepixel electrode starting next to the extension of the second commonelectrode pattern.
 14. The method of claim 11, wherein a first helicalturn of the pixel electrode is disposed between the first commonelectrode pattern and a first helical turn of the second commonelectrode pattern.
 15. The method of claim 11, wherein the common lineis formed as one unitary pattern with the common electrode.
 16. Themethod of claim 11, wherein the capacitor electrode has a substantiallyrounded side along the substantially circular opening of the firstcommon electrode pattern.
 17. The method of claim 11, wherein fourneighboring pixel regions correspond to red, green, blue and whitecolors, respectively.
 18. The method of claim 11, wherein the capacitorelectrode and the common electrode overlap to form a first storagecapacitor.
 19. The method of claim 18, wherein the capacitor electrodeoverlaps a previous gate line of a previously neighboring pixel regionto form a second storage capacitor.
 20. A method of forming an arraysubstrate for an in-plane switching liquid crystal display device,comprising: forming a gate line having a gate electrode, a commonelectrode having first and second common electrode patterns, and acommon line substantially parallel to and spaced apart from the gateline on a substrate using a first mask process, wherein the first commonelectrode pattern is substantially rectangle-shaped and has asubstantially circular opening in the middle thereof, and the secondcommon electrode pattern is disposed in the substantially circularopening and has a substantially gyre shape; forming a gate insulatinglayer on the gate line, the common electrode and the common line;forming a data line that crosses the gate line to define a pixel regionhaving an aperture area, a source electrode extending from the dataline, a drain electrode spaced apart from the source electrode acrossthe gate electrode, a semiconductor line under the data line and havingthe same pattern shape as the data line, and a semiconductor layerextending from the semiconductor line over the gate electrode and underthe source and drain electrode using a second mask process, wherein thesource and drain electrodes overlap opposite end portions of the gateelectrode, the semiconductor layer being exposed between the source anddrain electrodes, and the gate electrode, the semiconductor layer, thesource electrode and the drain electrode forming a thin film transistor;forming a passivation layer over an entire surface of the substrate tocover the thin film transistor and patterning the passivation layerusing a third mask process to form a drain contact hole to expose aportion of the drain electrode; and forming a capacitor electrode thatoverlaps the first common electrode pattern, and a pixel electrodedisposed within the substantially circular opening and having asubstantially gyre shape along the second common electrode pattern usinga fourth mask process, wherein the capacitor electrode is connected tothe thin film transistor, and the pixel electrode and the second commonelectrode pattern each have the substantially gyre shape, wherein theaperture area is substantially gyre shaped.
 21. The method of claim 20,wherein the second common electrode pattern extends from the firstcommon electrode pattern.
 22. The method of claim 21, wherein the pixelelectrode extends from the capacitor electrode, the extension of thepixel electrode starting next to the extension of the second commonelectrode pattern.
 23. The method of claim 20, wherein a first helicalturn of the pixel electrode is disposed between the first commonelectrode pattern and a first helical turn of the second commonelectrode pattern.
 24. The method of claim 20, wherein the common lineis formed as one unitary pattern with the common electrode.
 25. Themethod of claim 20, wherein the capacitor electrode has a substantiallyrounded side along the substantially circular opening of the firstcommon electrode pattern.
 26. The method of claim 20, wherein fourneighboring pixel regions correspond to red, green, blue and whitecolors, respectively.
 27. The method of claim 20, wherein the capacitorelectrode and the common electrode overlap to form a first storagecapacitor.
 28. The method of claim 27, wherein the capacitor electrodeoverlaps a previous gate line of a previously neighboring pixel regionto form a second storage capacitor.
 29. An array substrate for use in anin-plane switching liquid crystal display device, comprising: a gateline on a substrate; a data line crossing the gate line to define apixel region having an aperture area; a semiconductor line under thedata line and having the same pattern shape as the data line; a thinfilm transistor disposed at one corner of the pixel region and connectedto the gate and data lines, the thin film transistor including sourceand drain electrodes and a semiconductor layer extending from thesemiconductor line; a common line spaced apart from and substantiallyparallel to the gate line; a capacitor electrode overlapping a previousgate line of a previously neighboring pixel region; a pixel connectingline substantially parallel to the data line within the pixel region andconnected to the capacitor electrode and the drain electrode of the thinfilm transistor; a common electrode including a plurality of commonelectrode patterns, each of the common electrode patterns divided intotwo parts by the pixel connecting line without overlapping the pixelconnecting line; and a pixel electrode within a substantially circularopening and including a plurality of pixel electrode patterns withoutoverlapping the common line, wherein an outermost common electrodepattern is substantially rectangle-shaped within the pixel region andhas a substantially circular opening in the middle thereof, and othercommon electrode patterns are shaped substantially like semicirculararcs, wherein an innermost pixel electrode pattern has a substantiallyrod shape and is disposed within an area of pixel connecting line, andother pixel electrode patterns have a substantially semicircular-arcshape, and wherein the plurality of common electrode patterns and theplurality of pixel electrode patterns form substantially circular bandshaped aperture areas.
 30. The array substrate of claim 29, wherein thepixel electrode overlaps portions of the pixel connecting line anddirectly contacts the pixel connecting line.
 31. The array substrate ofclaim 29, wherein the common electrode overlaps portions of the commonline and directly contacts the common line.
 32. A method of forming anarray substrate for use in an in-plane switching liquid crystal displaydevice, comprising: forming a gate line having a gate electrode and acommon line substantially parallel to and spaced apart from the gateline on a substrate using a first mask process; forming a gateinsulating layer on the gate line and the common line; forming a dataline that crosses the gate line to define a pixel region having anaperture area, a source electrode extending from the data line, a drainelectrode spaced apart from the source electrode, a pixel connectingline extending from the drain electrode and substantially parallel tothe data line, a capacitor electrode over a previous gate line extendingfrom the pixel connecting line, a semiconductor line under the data lineand having the same pattern shape as the data line, and a semiconductorlayer extending from the semiconductor line over the gate electrode andunder the source and drain electrode using a second mask process,wherein the source and drain electrodes overlap opposite end portions ofthe gate electrode, the semiconductor layer being exposed between thesource and drain electrodes, and the gate electrode, the semiconductorlayer, the source electrode and the drain electrode form a thin filmtransistor; forming a photoresist pattern on the thin film transistorusing a third mask process, the photoresist pattern including two firstsymmetric open portions separated from the pixel connecting line withoutoverlapping the pixel connecting line and two second symmetric openportions separated from the common line without overlapping the commonline; etching the gate insulating layer using the photoresist pattern asan etch mask to expose the common and pixel connecting lines under thetwo first symmetric open portions; forming a transparent conductivelayer on an entire surface of the substrate having the photoresistpattern; and removing the transparent conductive layer on thephotoresist pattern by stripping the photoresist pattern to obtain acommon electrode and a pixel electrode, wherein the common and pixelelectrodes fit in the first and second symmetric open portions of thephotoresist, the common electrode including a plurality of commonelectrode patterns, and the pixel electrode including a plurality ofpixel electrode patterns, wherein an outermost common electrode patternis substantially rectangle-shaped within the pixel region and has asubstantially circular opening in the middle thereof, and other commonelectrode patterns are patterned to have substantially semicirculararcs, wherein an innermost pixel electrode pattern has a substantiallyrod shape and is disposed within an area of the pixel connecting line,and the other pixel electrode patterns are substantiallysemicircular-arc shaped, and wherein the aperture area is circular bandshaped.
 33. The method of claim 32, wherein the pixel electrode overlapsportions of the pixel connecting line and directly contacts the pixelconnecting line.
 34. The method of claim 32, wherein the commonelectrode overlaps portions of the common line and directly contacts thecommon line.
 35. An array substrate for an in-plane switching liquidcrystal display device, comprising: a gate line on a substrate; a dataline crossing the gate line to define a pixel region having an aperturearea; a gate pad connected to one end of the gate line; a data padconnected to one end of the data line; a gate pad terminal connected tothe gate pad; a data pad terminal connected to the data pad; asemiconductor line under the data line and having the same pattern shapeas the data line; a thin film transistor disposed at one corner of thepixel region and connected to the gate and data lines, the thin filmtransistor including source and drain electrodes and a semiconductorlayer extending from the semiconductor line; a common line spaced apartfrom and substantially parallel to the gate line; a common electrodeextending from the common line and including a plurality of commonelectrode patterns, wherein an outermost common electrode pattern issubstantially rectangle-shaped within the pixel region and has asubstantially circular opening in the middle thereof; a capacitorelectrode overlapping a previous gate line of a previously neighboringpixel region; a pixel electrode within the substantially circularopening and including a plurality of pixel electrode patterns; and apixel connecting line substantially parallel to the data line in thepixel region and connected to the capacitor electrode, the pixelelectrode and the drain electrode of the thin film transistor, whereinthe innermost pixel electrode pattern is shaped like a rod and disposedwithin an area of the pixel connecting line, wherein the pixel electrodeoverlaps portions of the pixel connecting line and directly contacts thepixel connecting line, wherein other pixel electrode patterns arepatterned to have semicircular shapes, and wherein the semiconductorline extends underneath the source and drain electrodes, the pixelconnection line and the capacitor electrode, wherein an innermostportion of the plurality of common electrode patterns is substantiallycircular band shaped, and wherein the aperture area is circular bandshaped.
 36. The array substrate of claim 35, wherein the plurality ofcommon electrode patterns are arranged in an alternating pattern withthe plurality of pixel electrode patterns.
 37. The array substrate ofclaim 35, wherein the innermost portion of the pixel electrode patternis disposed at a center portion of the pixel region where the commonline and the pixel connecting line cross.
 38. The array substrate ofclaim 35, wherein the capacitor electrode pattern is connected to thethin film transistor though the pixel connecting line.
 39. The arraysubstrate of claim 35, wherein four neighboring pixel regions correspondto red, green, blue and white colors, respectively.
 40. The arraysubstrate of claim 35, wherein the pixel and common electrode patternsare disposed within the substantially circular opening, except theoutermost common electrode pattern.
 41. A method of forming an arraysubstrate for use in an in-plane switching liquid crystal displaydevice, comprising: forming a gate line having a gate electrode, acommon electrode including a plurality of common electrode patterns, agate pad connected to one end of the gate line and a common linesubstantially parallel to and spaced apart from the gate line on asubstrate using a first mask process, wherein an outermost commonelectrode pattern is substantially rectangle-shaped and has asubstantially circular opening in the middle thereof; forming a gateinsulating layer on the gate line, the common electrode, the gate padand the common line; forming a data line that crosses the gate line todefine a pixel region having an aperture area, a source electrodeextending from the data line, a drain electrode spaced apart from thesource electrode across the gate electrode, a pixel connecting lineextending from the drain electrode and substantially parallel to thedata line, a capacitor electrode over a previous gate line withextending from the pixel connecting line, a data pad connected to oneend of the data line, a semiconductor line under the data line andhaving the same pattern shape with the data line, and a semiconductorlayer extending from the semiconductor line over the gate electrode andunder the source and drain electrodes and pixel connecting line andcapacitor electrode using a second mask process, wherein the source anddrain electrodes overlap opposite end portions of the gate electrode,the semiconductor layer being exposed between the source and drainelectrodes, and the gate electrode, the semiconductor layer, the sourceelectrode and the drain electrode form a thin film transistor; forming apassivation layer over the data line, the source and drain electrodes,the data pad, the pixel connecting line, and the capacitor electrode;forming a photoresist pattern on the passivation layer to cover the thinfilm transistor using a third mask process, the photoresist patternhaving openings between the plurality of common electrode patterns andcontact openings exposing the gate and data pads; forming a transparentconductive layer on an entire surface of the substrate to cover thephotoresist pattern; and removing the transparent conductive layer onthe photoresist pattern by stripping the photoresist pattern to obtain apixel electrode, a gate pad terminal and a data pad terminal, whereinthe pixel electrode fits in the openings of the photoresist and directlycontacts the pixel connecting line, the pixel electrode including aplurality of pixel electrode patterns, wherein an innermost pixelelectrode pattern has a substantially rod shape and other pixelelectrode patterns are patterned to have semicircular shapes, wherein aninnermost portion of the plurality of common electrode patterns issubstantially circular band shaped, and wherein the aperture area iscircular band shaped.
 42. The method of claim 41, wherein the pluralityof common electrode patterns are arranged in an alternating pattern withthe plurality of pixel electrode patterns.
 43. The method of claim 41,wherein the innermost pixel electrode pattern is disposed at a centerportion of the pixel region where the common line and the pixelconnecting line cross.
 44. The method of claim 41, wherein the capacitorelectrode pattern is connected to the thin film transistor though thepixel connecting line.
 45. The method of claim 41, wherein the capacitorelectrode overlaps the outermost common electrode pattern and forms astorage capacitor with the overlapped portion of the outermost commonelectrode pattern.
 46. The method of claim 41, wherein the pixel andcommon electrode patterns are within the substantially circular openingexcept the outermost common electrode pattern.